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MANUAL OF

Wireless Telegraphy
and Telephony

c^^

^ ^! I ') n /^ .^

A. FREDERICK COLLINS

THIRD EDITION, REVISED AND ENLARGED

FIRST THOUSAND

NEW YORK

JOHN WILEY & SONS

London: CHAPMAN & HALL, LIMITED

1913

A. FREDERICK COLLINS

(First Edition Entered at Stationers' Hall)

• c
e

THE SCIENTIFIC PRE88

ROBERT ORUMMORO AND COMMMT

BROOKLYN, N« Vi

PREFACE TO THE THIRD EDITION

& The tremendous strides in wireless during the past

ten years have necessitated a revision of this Manual.
^ In the matter of improved apparatus the ahernating
^ current transformer has largely taken the place of the
^ induction coil and the auto receptor has all but superseded
the coherer receptor in practical installations, with the
result that both the working and the efficiency of stations
have been greatly improved.

Due to these and other advances it has been found
expedient to segregate the chapter on The Apparatus of a
Commercial Station and treat the transmitting and the
receiving instruments separately. Aerials is a subject to
which much new text has been added since the flattops
oiT aerial has come into general use together with better
methods of suspension than those treated of in the previous
editions of this Manual. Furthermore, considerable useful
data have been appended under the caption of Suggestions
to Operators relating to the management of stations.

On the other hand the list of stations of the various
operating companies and the Army and the Navy has

290028

Iv PREFACE

been omitted as being unnecessary, since the U. S.
Government Printing Office publishes a booklet giving
the names, locations, call letters, wave lengths, and
types of apparatus of all ship and shore stations.

A. F. C.

The Anti-ers, Congers, N. Y.
January i, 1913.

PREFACE TO THE SECOND EDITION

Since the publication of the first edition of Mr.
Collins' Manual of Wireless Telegraphy the newer
art of transmitting articulate speech without wires has
been reduced to commercial practice.

Wireless telephony employs electric waves as does
wireless telegraphy, but the means for producing these
waves, as well as their characteristics, are quite different,
and in order to bring out the salient features there is
appended in this edition a clearly and concisely written
treatise by Mr. Newton Harrison.

By a careful perusal of the appended text the wire-
less operator will obtain a fair working knowledge of
the construction and operation of the wireless telephone,
and since the new apparatus is rapidly coming into
general use this information should prove of great value.

August I, 1909.

[ .

PREFACE TO THE FIRST EDITION

As every one interested in wireless telegraphy is
aware, there are numerous books on the subject; but
while this is true, there is very little information avail-
able for those who are, or who desire to become,
operators.

In preparing this manual my purpose has been to
give detailed and explicit instructions for wiring the
various types of sending and receiving apparatus now
in general use, the adjustment of the instruments,
tuning and syntonizing the circuits, testing the devices,
and finally the management of ship and shore stations.

The most proficient operators are those who com-
bine theory with practice, and if the principles involved
in the system he is working are clearly understood, the
adjustment and manipulation of a set will be rendered
much easier than where the results are striven for
blindly. Hence if this book is carefully studied and
the instructions are faithfully followed, many of the

difficulties usually encountered can be easily overcome

vm PREFACE

or circumvented by the operator, and he will be able
to send and receive messages with a greater degree of
accuracy and over considerably longer distances than
would otherwise be possible.

A. Frederick Collins.

The Antlers, Congers, N. Y.
August I, 1906.

CONTENTS

CHAPTER I

PAGE

A Simple Wireless Telegraph System i

Diagram of a Simple Transmitter 2

Coherer Receptor 4

Auto-detector Receptor 8

An experimental Transmitter 8

Coherer Receptor 10

Auto-detector Receptor 14

il iC It It

tt tt

li it

CHAPTER II

Elementary Theory 19

First Principles 19

Direct Current •. 20

Alternating Currents 22

Electric Charges 23

* * l^)arks 24

* * Oscillations 27

* ' Waves 30

Propagation of Electric Waves 31

The Ether. 35

Constants of the Oscillation Circuit 37

(a) Resistance 37

(b) Capacity 38

Open and Closed Oscillation Circuits 40

(a) Conductively Coupled Oscillation Circuits 41

{b) Inductively '* '' '' 42

CONTENTS

CHAPTER III

PAGE

Apparatus of a Cohmercial Station 44

Sending Instruments 44

Sources of Current 44

Morse Keys 45

(a) Key for Coherer Receptor 45

(b) Key for Auto-detector Receptor 46

Low- voltage Meters 47

The Induction Coil 47

Interruptors 48

(a) Spring Interruptor 48

(b) Mercury Turbine Interruptor 50

The Condenser 52

The Transformer 54

(a) Open Coil Transformer 54

(b) Closed Coil Transformer 54

Resistance and Impedance Coils 56

Spark-Gaps 56

High Tension Condensers 58

(a) Leyden-jar Battery 58

(b) Glass Plate Battery 58

Inductance Coils 58

(a) Conductive Coil 58

(b) Inductive Coils 58

Aerial Switch 60

Anchor Gaps 61

Hot-wire Ammeter 61

CHAPTER IV

Apparatus of a Commercial Station 63

Receiving Instruments 63

The Coherer Receptor 63

(a) Coherer 63

(b) Tuning Coil 64

(d) Condenser 65

(e) Relays 65

CONTENTS xi

PAGE

(/) Tappers or De-coherers 67

{g) Morse Registers : 67

(A) Choking Coils 68

[i ) Polarized Cells. » 68

{j ) Dry Cells 69

Instruments:

{a) Relay Testing-coil . . . .' 69

(6) Tuning Device , 69

Auto-detector Receptors 71

Magnetic Detector Receptor 71

(a) The Detector 71

{b) Tuning Coil 72

{d) Telephone Receivers 74

Crystal Detector Receptors 74

(a) Crystal Detectors 74

(6) Fixed Condenser 76

{d) Variable Condenser 76

{e) Telephone Receivers 76

Electrolytic Detector Receptor 76

{a) Electrolytic Detector 76

{b) Tuning Transformer 76

{d) Potentiometer 76

(e) Dry Cells 76

(/ ) Condensers 78

(g) Telephone Receivers 78

CHAPTER V

The Aerial Wire System 79

The Signalling Distance 79

The Aerial Wire 81

Types of Aerials 82

(a) Straight Vertical Aerial 82

(6) Oblique Aerial 82

{d) Umbrella Aerial 85

Kli CONTENTS

The Mast 86

Portable Mast 92

Methods of Suspension 93

(b) Commercial Methods of Suspension 93

Leading-in Insulator 95

The Grounded Terminal 96

The Operating Room 98

Aerial Wires and Grounds for Field Work loi

(a) Balloons 101

(b) Kkes loi

CHAPTER VI
WnuNG Diagrams for Transmitters 105

Wiring Diagrams of Ordinary Induction Coil Interruptor and

Condenser 106

Wiring Diagram of Induction Coil with Independent Spring

Interruptor 107

'* '* Mercury Turbine

Interruptor 109

Induction Coil with Electrolytic Interruptor no

Keys no

(a) Key with Condenser in

(b) * * ' * Magnetic Blow-out in

Diagram of Simple Induction Coil Transmitter 112

** ** ** Transformer Transmitter 112

** Primary or Low Tension Circuits 114

'* Conductive-coupled Oscillation Circuits 114

** Inductive-coupled Oscillation Circuits 115

" ** a Complete Telefunken Transmitter 116

** " '* '* Marconi Transmitter 118

CONTENTS

CHAPTER VII

PAGE

Wiring Diagrams for Receptors

Circuit Connections 121

Diagram of Simple Open-circuit Resonator 122

Elementary Diagram of Detector and Cell Circuit 122

Diagram of Conductive-Coupled Resonator 124

' * * ' Inductive-coupled Resonator 126

Wiring Diagram of Relay Connections 1 26

Aerial Wire System, Coherer, and Relay

Circuits 127

Internal Circuits 131

Complete Receptor 132

Receptor with Magnetic Detector 132

' * ' * Electrolytic and Crystal

Detectors 135

I (

C I

< <

CHAPTER Vm

( (

< i

The Apparatus in Action 139

Action of an Induction Coil 139

a Transformer 143

Simple Sending System 144

Conductive-coupled Sending System 146

an Inductive-coupled Sending System 148

a Receiving System 150

Conductive-coupled Receiving System 150

Coherer 153

Polarized Relay 153

Tapper 153

Morse Register 154

an Electrolytic Detector 154

a Magnetic Detector 155

* * Crystal Detector 155

( t

1 1

i (

( (

( I

H it

XIV - CONTENTS

CHAPTER DC

PAGE

Adjusting and Operating the Instruments 157

Notes on Adjusting , . 157

Adjustment of Instruments in the Primary Circuit 158

Adjusting the Spark-gap 160

To Tune a Coupled Transmitter 160

to Emit a Given Wave-length 162

a Coherer Receptor 167

Adjustment of Receiving Instruments 169

(a) Coherer 169

(b) Relay 169

(d) Morse Register 1 70

Testing the Receptor 173

Adjustment of Electrolytic Receptor 173

Magnetic Detector 1 74

Crystal Detector 174

Learning the Alphabetic Codes 175

Wireless Telegraph Codes , 176

ft t(

CHAPTER X

Different Makes of Equipment 177

The Marconi System 1 79

The Telefunken System 192

The Signal Corps, U. S. A., Portable Apparatus 194

The United System 206

CHAPTER XI

Suggestions to Operators » 208

General Information 210

Rates for Wireless Messages 212

Marconi Stations Along the Atlantic Seaboard 214

Locating Ships in the Atlantic Ocean 215

Offices of the Marconi Company 216

List of U. S. Ship and Shore Stations 217

CONTENTS XV

PAGE

Type of Apparatus Installed 217

U. S. Army Wireless Telegraph Stations 217

Where to Apply for Positions ^218

Service Regulations for Commercial Operators 223

Instructions for Naval Operators 239

Distress Signals 242

Wireless Call Book 243

CHAPTER XII

Wireless Telephony 244

Means for Producing Electric Waves 244

General Method Employed 245

The Transmitter 246

The Oscillation Arc 248

Application of Arc to Wireless Telephony 249

Theory of Oscillation Arc 251

Use of Magnetic Field 252

Oscillograph Tubes 252

The Receptor 259

Tests of Wireless Telephone 359

APPENDIX

List of Books on Wireless Telegraphy. 261

Glossary of Wireless Words, Terms, and Phrases 271

Index 28r

MANUAL OF

WIRELESS TELEGRAPHY

CHAPTER I
A SIMPLE WIRELESS TELEGRAPH SYSTEM

A WIRELESS TELEGRAPH operator must not only be
able to send and receive messages, but he must also be
thoroughly familiar with the apparatus employed, so
that should occasion require, as, for instance, when a
new set arrives from the makers, he can install the in-
struments, adjust them to their maximum efficiency
and sensitiveness, and overhaul them when they get
out of order.

While a complete equipment of instruments such as
is used for commercial work is more or less complicated
to the beginner, if he will bear in mind that all the diflfer-
ent types are evolved from and still retain the same
simple original features that made wireless telegraphy
possible, and that the improvements in the art are re-
sponsible for the additional arrangements, it will not

A SIMPLE WIRELESS TELEGRAPH SYSTEM

be difficult for him to grasp the more complex details
after a simple system is understood.

Diagram of a Simple Transmitter.^For this reason
careful study should be devoted to the following diagrams,

Induction Coil

.A.

Interruptor

Condenser

Copper PiaU
In Eartn

Fig. I. — ^Transmitter of a Simple Wireless Telegraph System.

Figs. I and 2, or Figs, i and 3, which when taken together
represent a wireless telegraph system in its simplest form ;
and having these well in mind it will be easy for the
student to follow the connections of any system now in
use, since all are merely modifications of one of the two
fixed types.

By referring to Fig. i a diagram of the transmitting
apparatus for sending wireless messages will be seen.

A SIMPLE IVIRELESS TELEGRAPH SYSTEM 3

The different parts of the instrument are clearly marked,
and it will be observed that the aerial wire — which is
simply a bare copper wire suspended in the air by a
mast, and insulated from it — is connected to one of the
spark-balls, forming one side of the spark-gap. To the
opposite spark-ball a similar copper wire is connected
which leads to the earth and is there attached to a metal
plate, usually of zinc or copper. This is termed the
ground-wire. This part of the transmitter comprises the
oscillator system, and in this case it is also called the
radiator, since it radiates the energy into space.

On opposite sides of the spark-gap formed by the
brass balls, or spheres, the terminals or ends of the
wire of the secondary coil of an induction coil are con-
nectcd. In the diagram the secondary is indicated by
a f.nc zigzag line, since this coil is built up of fine wire.
The circuit derived by connecting the secondary coil with
the spark-gap is termed in wireless telegraph parlance
the charging system. The inductor, or primary coil of
the induction coil, is shown as a heavy zigzag line,
and the ends of this coil are connected to a battery, or
other source of electromotive force, and a telegraph key
through the medium of an interrupior. This constitutes
the energizing system. Although the primary and sec-
ondary coils are portions of different circuits or systems of
the transmitter, they are allied very closely in the apparatus
and together with the interruptor and its condenser make
up the induction coil.
. The battery ^Qjijie^^ed to the primary coil generates

4 A SIMPLE IVIRELESS TELEGRAPH SYSTEM

the initial current that flows through the circuit when
it is closed, and it is this current that energizes the sec-
ondary coil which in turn charges the radiator system.
A telegraph key is, of course, employed to break up
the current from the battery that flows through the
primary coil, into the alphabetic code of dots and dashes.
The aerial wire and the earth-wire coupled through the
spark-gap form an open circuit, for, as may be readily
seen, they end abruptly; the secondary coil and the spark-
gap connected together form a closed circuit, as well as the
primary coil and its connections through the key and
battery. Since the aerial and earth wires are located
outside the station, the open circuit produced is some-
times termed the external circuit, while the primary and
secondary circuits are likewise occasionally referred to
as internal circuits, these being located within the station.

If the embryo operator will remember that the primary
circuit, the secondary circuit, and the radiating system,
i.e., the aerial and ground and the spark-gap, may be
considered as distinct circuits, just as the fire-box, boiler,
and engine may be treated as individual parts of a
whole, he will be able to gain a clearer conception of
the system formed when they are joined in combination.

Diagram of a Simple Coherer Receptor. — The receptor,
as the entire receiving arrangement is designated, com-
prises, as Fig. 2 shows, a similar aerial wire and a similar
ground-wire to those employed in the transmitter. The
aerial wire is connected with one side of the coherer, the
other side of which is grounded, by the wire leading to the

A SIMPLE WIRELESS TELEGRAPH SYSTEM

earthed metal plate. This forms an open circuit and
is termed the resonator system. It corresponds to and
receives the energy emitted by the radiator system.
From opposite sides of the coherer \sdres lead to a dry cell

Copper Plate ii^
Earth

Fig. 2. — ^Diagram of a Simple Coherer Receptor.

and the magnets of a relay ^ and these are connected when
a message is to be received through a small switch. A
second circuit is provided by connecting the contact-
points of the relay with a batter}^ of dry cells and a buzzer,
soimder, or Morse register which indicates the signals.

6 A SIMPLE IVIRELESS TELEGRAPH SYSTEM

Across this circuit and parallel with it there is a vibrating
tapper for decohering the filings of the coherer so that
another impulse can be received.

When the energy radiated by the aerial wire of the
sending station impinges upon the aerial wire of the
receiving system the filings of the coherer are drawn
together; when this action takes place the current from

Copper Plate In
Ground

Fig. 3. — Diagram of a Simple Auto-detector Receptor.

the dry cell flows through the relay magnets, the arma-
ture, carrying a platinum point, is drawn down by mag-
netic attraction, and the stationary and movable points
are brought into contact with each other, closing the
circuits in which are inserted the Morse register or indi-
cating device and the decohering tapper.

A SIMPLE IVIRELESS TELEGRAPH SYSTEM

8 A SIMPLE IV IRE LESS TELEGRAPH SYSTEM

Diagram of a Simple Auto-detector Receptor. — ^The
accompanying diagram, Fig. 3, represents the simplest
type of receptor and one capable of receiving messages
over long distances. It is formed of an aerial wire
connected to the slide of the tuning coil. The opposite
end of the tuning coil leads to the ground. One side
of a condenser is connected Mrith the slide of the tuning
coil and the opposite side of the condenser connects with
one terminal of a crystal detector, while the other terminal
of the detector connects with the ground wire. A tele-
phone receiver is shunted around the detector as shown.

An Experimental Transmitter. — ^An. experimental trans-
mitter may be constructed at a small cost, and much
valuable experience may be gained with it. An induc-
tion coil, or Ruhmkorff coil, giving a J -inch spark, may
be purchased from a dealer in electrical supplies for
five or six dollars. A coil of this size will give excellent
results for 50 or 100 feet without grounding the spark-gap
of the transmitter or the detector of the receptor, but by
merely placing the metal plates, which should be about
12 inches on the side, on the floor; aerial wires 12 oi: 15
feet in length should be provided, and suspended by
insulators from the walls. Intervening objects, such as
walls, windows, etc., will not interfere with the transmis-
sion of the waves and hence the sender and receiver can be
placed in different rooms. This size coil with masts will
also work satisfactorily over water a distance of ^ to i
mile if aerial wires 25 to 30 feet high, and rectangular
earth-plates 3X4 feet on the side are used.

A SIMPLE IVIRELESS TELEGRAPH SYSTEM 9

Having obtained the coil it will be necessary to provide
the brass balls for the spark-gap as shown in the line
cut, Fig. 4; the balls may be J or f of an inch in diam-
eter, and these are fitted to the coil by attaching stiff
brass wires to them and through the binding posts that
form the terminals of the secondary coil. An ordinary
Morse telegraph key and a battery of six or eight dry
cells connected in series with the primary posts of the
induction coil completes the transmitter, except that of
attaching the aerial and ground wires to the stiff wires
carrying the spark-balls.

The coil is furnished with an interruptor^ a device
which automatically makes and breaks the current
flowing through the primary coil when the key is depressed,
and the spring vibrator must be so adjusted that when
the telegraph key is open the stationary contact point
just touches the bit of platinum soldered to the spring
carrying the armature. The spark-gap balls should
be so adjusted that they are not more than J inch apart,
as this gives much better results than when set at
their greatest distance, namely, J inch, the reason being
explained in the elementary theory to follow. The
coil and the key should be mounted on a base of
wood.

If the apparatus is to be used out-of-doors the aerial
wires of both the sender and receptor must be suspended
from the masts by glass insulators, or from a convenient
pole projecting from a third- or fourth -story window or
the top of a house, and the wire fastened to the opposite

A SIMPLE WIRELESS TELEGRAPH SYSTEM

side of the spark-gap to the sheet of metal embedded in
the earth or immersed in the water, as the case may be.
The sending and receiving wires leading from the instru-
ments inside the station to the outside must be ex-
v:eedingly well protected by glass or porcelain insulators
from the building and mast or the high-tension energy

iM~

'=^^

Fig. s. — A Simple Coherer.

will be dissipated before it can send out eflFective
waves.

An Experimental Coherer Receptor. — Nearly every-
thing needed for the receptor can be purchased in the
open market, unless it is the coherer; and this, besides
being easily made, is well worth while for the experience
gained. A simple one is made of two binding posts,
having two set screws and two holes in each for the
insertion of wires, and these are screwed to a base of wood
2 inches wide, 3 inches long, and \ inch thick at a distance
of 2 inches, as shown in Fig. 5 ; two brass wires -^ inch

^SIMPLE IVIRELESS TELEGRAPH SYSTEM

12 A SIMPLE IVIRELESS TELEGRAPH SYSTEM

in diameter and i^ inches long are inserted in the upper
hole of each binding-post; these wires are termed con-
dtcctor-plugs and fit snugly into a bit of glass tubing i
inch long; before the plugs are inserted, however, a pinch
of nickel and silver filings in equal proportions are placed
in the tube; the filings are best made with a clean, coarse
file, using a nickel five-cent piece and a silver dime.

The relay, known as a pony relay, is wound to a resist-
ance of 1 50 ohms, and its cost is in the neighborhood of
$2.50. Relays having a higher resistance can be pur-
chased which makes them more sensitive, but the one
mentioned will give excellent service. The tapper can
be supplied by using an ordinary electric bell from which
the gong has been removed. Instead of a Morse register,
as is used in long distance sets and which cost about $40.00,
a Morse telegraph sounder, costing $1.75, can be sub-
stituted, or what is even better and cheaper for the
experimental set is a buzzer, costing only 50 cents. The
resistance of the magnet coils of the buzzer and the tapper
should be the same, though they are worked in parallel
from the same battery. The resistance may be 4 ohms,
the usual value, though if they are more it is not material.
All these instruments may be purchased from a supply-
house.

The base of the coherer should be screwed to a base-
board large enough for the tapper, the relay, and the
buzzer. The tapper is attached to the base-board so
that the hammer, which is intended to tap the gong,
will instead tap the glass tube of the coherer. The

A SIMPLE fVIRELESS TELEGRAPH SYSTEM 13

relay may be place4 conveniently on the right, and the
buzzer or sounder, if the latter is used to indicate the
signals, on the left, all being plainly shown in the photo-
graph Fig. 6. The instruments should now be connected
up as illustrated in the diagram Fig. 2; the aerial wire
and the earth-wire are inserted in the upper holes of the
coherer binding posts, as are also the ends of the wire
that connects the coherer, the dry cell and the relay
magnets.

The binding posts of the relay contacts are connected
with the posts of the buzzer and dry battery of four cells,
with the tapper connected in parallel. When the instru-
ments are properly connected up it is best to test them
in a room, with the sender and receptor not too far apart.
To adjust the coherer and relay is the most difficult and
tedious process involved in getting the instruments to
work, and is only accomplished by practice and per-
severance; by heeding the following suggestions, however,
much time and trouble may be saved.

The screws of the relay are first adjusted so that the
armature will have a free movement of only ^j of an inch,
and when the platinum point of the armature is drawn
into contact with the stationary point the armature just
clears the polar projections of the magnets. The tension
of the coiled spring attached to the armature must be
very feeble and only enough to draw the latter back
from the magnets when there is no current flowing
through them. This done, connect in the two dry cells
with the coherer, through the switch; th^n unscrew one

14 A SIMPLE IVIRELESS TELEGRAPH SYSTEM

of the conductor-plugs of the coherer and, gently twisting
the wire, force it in the glass tube against the filings until
the current begins to flow through the circuit and the
magnets of the relay attract the armature. Tap the
coherer with a pencil while adjusting to keep the filings
decohered. When the proper balance is secured between
the coherer and the relay, the latter should operate when
the switch is closed, for the potential of the current from
the dry cell is sufficient to cohere the filings, and when
this takes place the relay will close the second circuit.
Under these conditions if the key of the transmitter is
pressed, a spark will pass between the spark-balls and
the tapper and buzzer of the receptor will operate in
unison with it.

An Experimental Auto-detector Receptor.^ — The appa-
ratus for this receptor, like the preceding one, may be
purchased from dealers in electrical supplies, or the
student can make all the parts, except the telephone
receiver, at little expense.

To make a tuning coil wind a layer of No. 20 single
cotton-covered magnet wire on a cardboard tube 3 inches
in diameter and 6 inches long. Coat the wire with shellac
varnish and when dry scrape the insulation off \ inch
wide the entire length of the coil. Make two hard-wood
cheeks 4 inches on the side and bore a ^-inch hole through
the center of each. Now thread the ends of a J-inch
brass rod having a length of 6f inches.

Put the wood cheeks on the tube, slip the rod through
the holes and cylinder and on one end screw a nut, and

A SIMPLE K^IRELESS TELEGRAPH SYSTEM 15

on the other a binding post. To the latter connect one
of the ends of the coil of wire. To the top of the cheek
screw another binding-post and to this secure a brass
rod -^ inch square and 7 inches long and bent as shown
in the cut. Make a metal slide with a spring contact
to fit over the rod which serves as a guide and the coil

Fig. 7.— Single-slide Turning CoiL

IS complete. The details of construction are clearly
shown in Fig, 7.

The condenser is built up of 6 sheets of tin foil i^
inches wide and 2 inches long and separated with leaves
of paper shellacked so that the alternate leaves of tin-foil
project on the opposite side. Place in a small box and
attach binding posts to the projecting ends,

A first-rate detector can be made by mounting on a

A SIMPLE IV I RE LESS TELEGRAPH SYSTEM

wood or hard rubber base 3 by 4 inches on the side, a
standard formed of two pieces of brass rod each of which
is i inch long. This permits the phosphor bronze spring
to be moimted in the position shown in Fig. 8. On top
of the standard a cross-bar is secured by a screw which
also passes through the spring and screws into the lower

Adjusting Screw

Standard"

Wire

CV-"H

Phosphore
Bronze Spring

Crystal of
Iron Pyrite

Brass Holder

Base

^^-1 Binding
Igl! p-Post

Wire

Fig. 8. — Simple Crystal Detector.

■^

part of the standard. The spring is^ sharpened at its
free end and bent over so that its point will rest on the
crystal in the holder, which is connected with the bbding
post. A very fine adjustment may be had by turning
the adjusting screw. Use a crystal of carbonmdum, iron
pyrite or silicon. Procure a telephone receiver wound to
as high a resistance as possible. No battery is required
with this receptor. Hooked up in accordance with the

A SIMPLE IVIRELr.SS TELF.GR/IPH SYSTEM

1 8 A SlfAPlE WIRELESS TELEGRAPH SYSTEM

diagram, Fig. 3, and adjust the detector until the incoming
messages are loudest; now by moving the slide of the
tuning coil to and fro the strength of the messages can
be materially increased. Fig. 9 shows the auto-detector
re :eptor set up and ready for use.

CHAPTER II

ELEMENTARY THEORY

First Principles. — In ordinary telegraphy a direct cur-
rent generated by a battery or a dynamo is employed to
send the alphabetic code over the wire, the dots and
dashes being formed by making and breaking the circuit
by means of a key. In the telephone a direct current is
also employed as the initial source of energy, but this
is transformed into an alternating current by a small
induction coil before the undulations representing articu-
late speech are transmitted over the circuit. In the wire-
less telegraph a direct current is used primarily and this
is transformed into alternating currents, when these arc
converted into oscillating currents and the latter are
finally metamorphosed into electric waves which arc
then propagated through space. It will thus be observed
that the principles underlying wireless telegraphy are
more involved, and the apparatus for producing these
changes of energy successively are more complex, than
in ordinary telegraphy and telephony. If, however, the
action of low-voltage direct and low-frequency alternat-
ing currents are mentally clear to the student, the phe-

ELEMENTARY THEORY

nomena of electric oscillations and electric waves will
follow logically and be easily understood.

Direct Current. — Electricity flowing continuously
through a wire in one direction is termed a direct current.
Such a current may be generated by a battery or a dynamo

Fig. io. — Hydraulic Analogue of a Direct Current.

and although there is no perceptible movement of matter
along the circuit, yet the electricity flows through the
molecules of wire very much as water flows through a pipe.
The action of a direct current may therefore be graphi-
cally illustrated in the following manner: Let A^ Fig.
IO, represent a centrifugal pump, and B a continuous pipe
connecting the outlet of the pump with its own inlet.
If now the pipe and the pump are filled with water and
the wheel of the pump is rotated, then obviously the

ELEMENTARY THEORY

water will flow through the circuit in the direction indi-
cated by the arrows. In order to cause the water to
circulate, an expenditure of energy is of course required
and hence the wheel of the pump must be connected to
some external source of power.

Similarly, now, if one of the elements of a battery A,
Fig. II, is connected by a length of wire B to its opposite

Fig. II. — Direct Current Produced bv a Voltaic Cell.

element, the chemical action of the battery will generate
a continuous current, and this will flow through the wire
circuit unidirectionally as the water flowed through the
endless pipe. A direct current dynamo can be substituted
for the battery, and the current generated by the coils
of wire moving through the magnetic field w^ill flow
through the circuit as before.

ELEMENTARY THEORY

Alternating Currents. — If the continuous water-pipe B
IS connected to a valveless reciprocating pump i4, as
indicated in Fig. 12, instead of the centrifugal pump
shown in Fig. 10, the water in the pipe will obviously

Fig. 12. — Hydraulic Analogue of an Alternating Current.

flow first in one direction and then in the other, alter-
nating with every reversal of the piston.

Likewise if a wire B is attached to the secondary
terminals ^ of an induction coil as in Fig. 13, the current
flowing through it will move to and fro, alternating in
its direction periodically. It is this low-frequency cur-
rent that is employed to charge the oscillation system
of a wireless telegraph transmitter. It is possible to

ELEMENTARY THEORY

illustrate in a measure the transformation of an inter-
rupted low-voltage direct current into alternating high-
potential currents as produced by the induction coil,
but the analogue becomes as intricate and difficult of
comprehension as the electric action which it is intended
to represent, and it must be borne in mind that hydraulic

wwwv

Fig. 13. — Alternating Current Produced by Secondary of an

Induction Coil.

analogies must not be taken too literally, since with
electricity there is no tangible transfer of matter.

Electric Charges. — ^When a Leyden jar is charged
by an induction coil one of the coatings will be positively
dectrified and the other and opposite coating negatively
electrified, the glass jar separating the t^vo coatings of
tin-foil forming an inductively insulating medium between
them. When the high-potential currents produced at the
terminals of the secondary of the induction coil, — and

24 ELEMENTARY THEORY

these currents, which, as previously cited, are of an alter-
nating character, — are impressed upon the aerial wire and
the grounded wire, these receive and store up the energy
exactly like the coatings of a Leyden jar; when these
opposite arms or wires are changed to their maximum
capacity and to the opposite signs, namely, positively and
negatively, the charges rush together in their efforts to
equalize the differences of potential and break down
or disrupt the air-gap between the balls and a brilliant
'spark takes place."

Electric Sparks. — If it is desired to produce light-
waves, it is only necessary to ignite some substance that
will burn with a bright flame, as a pine knot or a stream
of gas under pressure; or an electric current may be
used to heat the filament of a lamp to incandescence or
produce an arc between carbons; but the long invisible
electric waves required in wireless telegraphy cannot be
obtained in this manner. For many years prior to
their discovery it was believed that waves of great length
could be set up in the ether, but it was a matter of much
speculation as to how to proceed. This and many other
things that are of importance in sending and receiving
wireless telegraph messages were ascertained by Heinrich
Hertz, a young professor at Bonn University, Germany,
in 1888.

The electric spark or disruptive discharge provides
the means for setting the charged arms of the aerial-wire
system into motion, when the energy thus released be-
comes oscillatory and is emitted as electric waves.

ELEMENTARY THEORY 27

There arc many forms of the disruptive discharge from
the long, attenuated, ribbon-like sparks shown in Fig. 14
to the thick, white, luminous discharge produced by
passing the same amount of energy through a shorter
spark-gap as shown in Fig. 15. The characteristics of
the discharge are changed somewhat by the type of inter-
ruptor used; where the initial current is made and broken
by a mechanical vibrating spring interruptor the spark
is bright, zigzag in form, and gives forth a sharp, crack-
ling sound when the oscillator-balls are not drawn too
far apart, but if a Wehnelt electrolytic interruptor is
used the discharge is less brilliant, its path arcuated, and
its sound hissing.

The object of using balls at the spark-gap instead of
points or disks is that the latter dissipates much of its
energy in brush discharges, that is, electrified particles of
air are thrown off especially from the positive terminal
immediately the system is charged, and this greatly
weakens the effectiveness of the succeeding disruptive dis-
charge. Where bails are used there are no sharp points
or edges to aid a brush or convective discharge and
which reduces in this way the resistance the air offers
to the passage of the current, but permits the charges of
the oscillator system to reach their highest values before
disruption occurs.

Electric Oscillations. — ^When a disruptive discharge
takes place between the spark-balls of an oscillation
circuit all the energy contained in the charge is not con-
sumed in breaking down the air of the gap. On the

28 ELEMENTARY THEORY .

contrary a very small amount of the total charge of elec-
tricity thus set into motion is used for the purpbse. What
becomes of the rest of the charge that is not consumed?
At the instant the spark springs across the gap it burns
out the air and the heated particles that result provide
almost as perfect a con'ductor for the high-tension cu:*-
rent as though a copper wire connected the spark-
balls. In other words, there is for the succeeding instant
no longer a break in the oscillator system, but a prac-
tically continuous conductor is formed, and this being
the case, the static charges, now combined in an active
and pertinacious current under high pressure, rushes first
to one end of the aerial wire, then back through the
spark-gap, now of no appreciable resistance, thence to
the end of the earth-wire, and repeats this process two
or more times before its energy is damped out.

Surging high-potential currents of this kind are termed
electric oscillations, and a clearer idea of why and how
an electric current oscillates through an aerial and earthed-
wire system when released by a disruptive discharge is
shown in Fig. i6. Let A represent a balance having a
lever of equal arms resting on a fixed knife-edge; B, Fig.
17, is understood to be an oscillator system charged by an
induction coil. It will be observed that in one of the
pans of the balance there is a small weight, and this
draws one arm down while of course the other arm is
raised proportionately, the resultant being a difference of
level. In this case the force of gravity tends to equalize
the two ends of the beam, bringing it to the same level.

ELEMENTARY THEORY

If the weight is removed gently and gravity is permitted
to equaUze the difference of level slowly, the beam will

Fig. 16. — Analogue of Electric Oscilhitions.

Positive Charge

Earth Wire

Negative Charge

Fig. 17. — Diagram showing how Oscillations are Produced.

come to rest when the balance has been estabhshed and
there will be no further movement; if, however, the

30 ELEMENTARY THEORY

weight in the pan is removed quickly, the upper end of
the beam will drive the lower end upward not only to
its normal level but beyond, and then the process is
reversed and the opposite end overshoots its level, and
so several swings or oscillations of the beam will take
place before it comes to rest.

Exactly so with electric oscillations in an aerial and
earthed-wire system; before the disruptive discharge takes
place, which is equivalent to removing the weight from
the pan of the balance, one side is charged positively
or, for the sake of following more closely the analogue
above, it is high, and the opposite side negatively or low;
under this condition the spark is produced releasing
the pent-up energy of either arm, and these, now forming
an electric current, seek to equalize the difference of
potential and to restore the electric level. If the resistance
of the spark-gap is not too great, the current will swing
to and fro several times, or oscillate, before coming to rest.

The electric oscillations in a radiator system may
range from 100,000 to 1,000,000 times per second, depend-
ing upon the electrical dimensions of the aerial and
earthed wire, or its inductance, capacity, and resistance. In
the case of the balance its physical properties determine
the period or length of time of each oscillation. Likewise
the electrical properties, namely inductance, capacity,
and resistance, of an oscillator system determine the
period of each oscillation of the surging current.

Electric Waves. — ^When an electric oscillation surges
through the aerial system of a wireless telegraph

ELEMENTARY THEORY 31

transmitter a small portion of its energy is used up by
the various opposing forces or resistances which it has to
overcome. But what becomes of that portion that is
not required for this purpose ? If a metal rod is heated,
let us say, to redness, it will send out the energy impressed
upon it in the form of waves in the air, and any object if
not too far away will receive the transmitted waves and
be heated to a certain extent by it. Similarly the aerial
wire of an oscillator system will radiate the energy im-
pressed upon it in the form of electric waves in the ether.
These waves are emitted at right angles to the aerial wire,
and like light and all other waves propagated by the
ether they travel at a velocity of about 186,500 miles
per second. The lengths of electric waves vary inversely
with the period of oscillation producing them, and
therefore to determine the wave-length it is only necessary
to divide the velocity by the number of waves per second.
The wave-lengths employed in wireless telegraphy are
from 200 feet to one fourth of a mile, and to obtain the
most efficient waves the period of oscillation must be
in accord with the electrical properties of the radiating
system where there are two oscillating circuits coupled
together. Like light-waves, * electric waves may be
reflected, refracted, and polarized, provided the mirror,
prism, or polarizing grid is of a size commensurate with

the length of the waves.

Propagation of Electric Waves. — There are two

theories to account for the manner in which electric

waves traverse distances so great that the curvature of

32 ELEMENTARY THEORY

the earth rises higher than the aerial wires. The writer
beUeves the waves are in all essential respects like those
of light, and that when two stations are located closely-
enough so that the sending and the receiving aerials are
in a direct visual line the waves are propagated in a
straight line, as shown in the diagram Fig. i8. If, on
the other hand, the receiving aerial is so far distant from
the sending station that the earth rises like a hill between
them, then the electric waves travel onward until the
higher strata of the air are reached, which act as a
reflector, when their direction is then changed and they
are propagated back to the earth's surface. This is
termed the jree-wave theory.

A second theory, and one much more widely held,
accounts for their transmission over obstacles by assuming
the electric waves to slide over the surface of the earth
or sea. As the spark-gap of the oscillator system is
located very near ground, considering the height of the
radiating aerial, it is assumed that the waves are emitted
only from this part of the system and are virtually
cut in half as shown in Fig. 19, while the lower half
of the waves would exist only as an image or reflection of
the upper half. The earth or sea is not a perfect con-
ductor, but is sufficiently so to permit the waves to skim
over their surfaces. This is briefly the sliding halj-wave
theory of electric-wave propagation. ■ Fortunately for
those who practice wireless telegraphy these theories
may be entirely ignored, for after the electric waves
have left the radiating aerial until they again impinge

ELEMENTARY THEORY

ELBMENT/1RY THEORY

C/2

3
orq

K
o

-<
rt

ELEMENTARY THEORY 35

upon the receiving aerial they need not concern the
operator.

The Ether. — It is impossible to say of what the ether
is composed, but it is a substance that is fifteen trillion
times lighter than the air, and when set into vibration
produces and propagates light and all other electro-
magnetic waves of whatever length. The following
illustration may make its functions clearer.

When a message is sent from one station to another
by wireless telegraphy the waves of course travel through
the air; but, while this is true, the air really has nothing
to do with their transmission. That is to say, the air
cannot propagate electrical energy as it does mechanical
energy. If a bell is rung in a vessel from which the air
has been exhausted, its vibrations cannot be heard, for
sound waves are conveyed through space by the particles
of air; oppositely, if an incandescent light is placed in
the vessel and a vacuum produced by means of an air-
pump, its light will shine forth even better than if the
air was present, for there is then nothing in the glass
but the ether.

The source of light and the eye constitute in reality a
wireless outfit, the first sending out trains of waves through
the ether like a radiating aerial wire, and the eye receives
them very much like a coherer; hence the latter is some-
times termed an electric eye. Light waves and waves
sent out by a wireless transmitter are identical in every
particular except that of wave-length, the first being
excessively short and the last exceedingly long.

36 ELEMENTARY THEORY

Light waves are produced by infinitely minute charges
of electricity upon atomic matter that have been set into
motion by the application of heat or by other means.
These charges move with extreme rapidity, the slowest
capable of impressing the human sight, vibrating 400
billion times per second, and the fastest 750 billion times
per second; these vibrations send out in the first in-
stance waves in the ether that approximate 271 ten-
millionths of an inch in length, which gives us the
sensation of red light, and in the last case, waves 165
ten-millionths of aa inch in length, that are seen as
violet light. If the electric charges vibrate faster than
those giving violet light or slower than those producing
red light, they are not visible, for the eye is not designed
to receive them. Shorter waves than the visible violet
give rise to ultra-violet radiations, and like those imme-
diately lower than the visible red, or infra-red as they
are termed, they are invisible. Yet the last-named
waves may be measured by the ten-millionths of an
inch.

When the length of the waves reaches a value approxi-
mating a thousandth of an inch, an inch, a foot, a rod,
or a mile they Can no longer be seen or felt, and their
presence can only be indicated by some physical appa-
ratus such as a coherer. Waves of this length are set
up by oscillating turrents surging on the surface of
masses, such as wires instead of gaseous atoms, and
it is the former w^e have to deal with in wireless
telegraphy.

ELEMENTARY THEORY

The Constants of the Oscillation Circuit. — ^These are
its resistance, inductance, and capacity, and may be
compared to the dimensions of a mass, hence they are
sometimes referred to as the electrical dimensions of a
circuit. These constants determine how the current
shall be damped out and what its rate of oscillation shall
be, as will be seen by a perusal of the following.

Time
Fig. 20. — Electric Discharge through a Large Resistance.

Resistance. — It has been previously shown that the
resistance of an oscillation circuit is practically negligible,
and this is true when the length of the spark-gap is cut
down to its proper working value. The resistance of the
spark-gap may, however, be so great that the disruptive
discharge will not set up an oscillating current but a
unidirectional current^ or a current flowing in one direction
only, just as we have seen how the beam of a balance

ELEMENT/IRY THEORY

may come to rest in a single swing. When an electric
discharge takes place through a large resistance the
current describes a smooth curve, as shown in Fig. 20;
but when the discharge is through a small resistance,
then it becomes periodic and oscillates until it reaches
zero, as shown in Fig. 21. The unit of resistance is the
ohm.

Time
Fig. 21. — Electric Discharge through a Small Resistance.

Capacity. — The capacity of an oscillation circuit is its
property to retain a charge of electricity, and to an extent
where its pressure or potential is high enough to break
down the air of the spark-gap. By increasing the capac-
ity of the oscillation system, as by inserting a condenser
or adding to the length or surface of the aerial wires, the
energy of the oscillations may be increased, and of course
in this way the effectiveness of the waves radiated will

ELEMEhlTARY THEORY 39

be inci eased. Charging the aerial-wire system consists
of distributing the high-potential active energy from
the terminals of the secondary of an induction coil over
the surface of the aerial and ground wires, the interposed
spark-balls, and condenser and inductance coil, if these
are included. The greater the capacity the slower will
be the period of the oscillations, since the charging process
must be repeated after each disruptive discharge. The
unit of capacity is the jarad, but, as this is too large for
ordinary purposes, a microfarady or one millionth of a
farad, is used instead.

Inductance.— A current of electricity always requires
a certain length of time to start and, once in motion, a
certain length of time to stop. In this respect it is like
the inertia of matter; for instance, a ball cannot put
itself into motion, and when thrown into the air it has
no power to stop, and would not if the resistance of the
air and action of gravity did not combine to make it.
Electricity acts similarly. The selj-induction, as this
property of the electric current is called, depends largely
upon the form of the wire, that is, whether it is straight
or coiled, and the material surrounding the circuit,
though usually this is air and represents unity. The
inductance of a circuit, like capacity, has the property of
slowing down the oscillations. The value of the prac-
tical unit of inductance is the henry; the henry, like
the farad, may be too great for convenience, when it
may be expressed by some practical dimension, as a
millihenry.

ELEMENTARY THEORY

Open and Closed Oscillation Circuits. — In simple
open -circuit systems where the spark-gap is placed
directly between the aerial and grounded wires and the
secondary terminals connected thereto, the constants of
resistance, capacity, and inductance determine the period
of oscillation and consequently the emitted wave-length,

Connecting Cord

Fig. 22. —Analogue of Tuned Oscillation Circuits.

just as a piano-string will vibrate to its own natural
period and send out sound-waves of a predetermined
length. In all commercial systems there are two oscil-
lation circuits and these are coupled^ or connected
together. Under these conditions the two circuits —
a closed one and an open one — must be tuned to each
other.
An analogous case is that of two pendulums, see dia-

ELEMENTARY THEORY

gram Fig. 22, with the free ends connected by a cord.
If the pendulums are of the same length, size, and
weight, then they would swing, with the cord binding
them together, in unison; but if one of the pendulums
was shorter or lighter than the other, then their periods

3
U

Condenser

To Coil

Closed O
Oscillation
Circuit Q

CO
Q.
CO

To Coil

Ground
Fig. 23. — Conductively Coupled Oscillation Circuits.

of oscillation would vary, and if coupled together with a
cord they would oppose each other, so that neither would
swing normally; in other words, they would be out of
phase, just as electric oscillations are when the. circuits
have different dimensions. In order that a larger amount
of energy may be delivered to the radiating aerial and
to better sustain the oscillations set up in it, commercial

ELEMENTARY THEORY,

installations have the open and closed oscillation circuits
either (a) conductively coupled, or, (b) indtictively coupled
together.

In a conductive coupled system the open circuit is
formed of the aerial and ground wires connected to the

3
O

c
o

'15

Condenser

Closed

Oscillation
Circuit

Ground
Fig. 24. — Inductively Coupled Oscillation Circuits.

tuning coil while the spark-gap and adjustable condenser
are connected direct to the tuning coil as shown in

Fig. 23.

In an inductive coupled system the aerial and ground
wires are connected with the primary of an oscillation
transformer, while the spark-gap and adjustable con-

ELEMENTARY THEORY 43

denser are connected to the secondary coil of the trans-
former as in Fig. 24.

The spark-gap in this case is placed in the closed
circuit, as is an adjustable condenser formed of a Leyden-
jar battery and a variable inductance coil.

Before the disruptive discharge takes place the secondary
of the induction coil charges the condenser until the
potential is sufficient to break down the air-space of the
spark-gap. When the spark passes the oscillating current
surges through the closed circuit and in a direct-coupled
system the energy of the oscillations reaches the open
or aerial-wire system by conduction.

In an inductive-coupled system the energy of the
oscillations in the closed circuit is transferred to the
open or aerial-wire circuit by induction. From the
aerial wire it is radiated into space as electric waves.

Like the pendulums in Fig. 22, the open and closed
circuits must be in tune with each other so that the periods
of oscillation of both may be identical. This is accom-
plished by changing the values of the inductance of the
tuning coil or coils and of the condensers. To determine
when the circuits are in tune a hot wire ammeter is placed
in the aerial wire and the values of inductance and capacity
are changed until the readings of the meter are maximum.

When receiving, the incoming electric waves impinge
upon the aerial wire and the energy is converted into
high-frequency oscillations in the open circuit and are
either conductively or inductively impressed upon the
closed circuit in which a detector Is placed.

CHAPTER III

THE APPARATUS OF A COMMERCIAL STATION

Sending Instruments. — ^The apparatus required for
sending commercial wireless telegraph messages comprises
(a) a source of current, such as a. primary or storage
battery, a direct or an alternating-current dynamo; (b)
an induction coil or a transformer; (c) a large current
telegraph key; (d) a regulating resistance or a reactance
coil; (e) a variable spark-^ap; (f) an adjustable condenser
such as a Leyden jar battery or a plate-glass condenser
and (g) a variable tuning inductance coil.

Sources of Current. — (a) The only primary battery
suitable for energizing induction coils is one formed of
Edison cells. The type S cell develops 0.7 volt and has
a capacity of 300 ampere hours. A battery of these
cells does not deteriorate when not in use and requires
no attention until the charge is completely exhausted.

(6) A storage battery is preferable to a battery of
primary cells where a current is available for re-charging.
The type known as the chloride accumulator will be
found very satisfactory. This battery is serviceable for
both portable and stationary work. Each cell has a
capacity of 7^ amperes for eight hours. .

THE APPARATUS OF A COMMERCIAL STATION 45

(c) Wherever a iio-volt current developed by a dynamo
can be had it will give the best resuhs. Where direct
current only is available aji induction coil must be used;
where alternating current is obtainable a transformer
will be required. An alternating current can be used
to energize an induction coil by using an electrolytic
or a mercury turbine interruptor in circuit therewith.

Morse Keys.™ There are two types of telegraph keys

Fig. 25. — Wireless Key for Coherer Receptors.
used in wireless transmitters, and the one chosen must
depend upon the kind of receptor that is used.

(a) The type of key used where a coherer and Morse
register form the indicating apparatus of a receptor is
shown m Fig, 25. It is a modified form of Morse key
and is of large dimensions. The handle is cf hard
rubber; the lever is some iive inches in length, and across
the contact-points of the key, in some systems, a con-

46 THE APPARATUS OF A COMMERCIAL STATION

denser is fitted to reduce the spark, while in others a
magnelic blaivout is provided for the same purpose. The
blowout consists of an electromagnet with pointed poles
placed at right angles to the contact-points. When the
circuit is broken the current is shunted through the coils
of the magnet and the magnetic field blows out the

Fig. id. — Wireless Key fur Aulo-Deleclor Receptors.

Spark. A key of this type will break a current of 20 to
30 amperes continuously, but is designed for slow opera-
tion.

{b) Where an electrolytic or other auto-dctcctor receptor
is employed the key usually has the appearance of an
ordinary Morse key for wire telegraphy. ' The former
is, however, built on more generous lines and is provided
with large platinum contacts, and where currents of over
20 amperes are to be broken the contacts are fitted with
thin brass rings which radiate the heat. For currents

THE APPARATUS OF A COMMERCIAL STATION 47

of over 20 amperes a condenser is shunted around the ■
contact-points. This type of key, shown in Fig. 26, is
capable of very rapid manipulation.

Low-voltage Meters. — An ordinary ammeter and
^'oltmeter are useful, though not always furnished, for
determining the current and voltage of the primary
circuit.

The Induction Coil.— Where the distance between the
sending and receiving stations is not great the coil is

Fig. 27.— Marconi lo-inch Induction Coil.

generally provided with a vibrating spring interrupter
mounted on the same base, while the interior of the base
contains the condenser. Such a coil is shown in the
experimental transmitter previously described, and coils
of this type may be purchased in the open market in
sizes ranging from those giving a ^-inch to a 12-inch
spark. Fig. 27 shows a Marconi lo-inch coil.

In the usual commercial systems the induction coil,

48 THE /IPP/tRATUS OF A COMMERCIAL STATION

interruptor, and condenser are mounted separately. An
induction coil proper consists of a care formed of a bundle
of soft-iron wires, and upon this are wound two layers of
heavy insulated wire termed the primary coily or inductor y
the ends of which are brought out and attached to
binding-posts. The long fine insulated wire forming the
secondary coil is wound around the primary coil but
is, at the same time, carefully insulated by a tube
of glass, hard rubber, pasteboard, or micanite. The
ends of the secondary coil are connected to insulated
binding-posts.

The secondary coil of a commercial transmitter is
wound with a larger wire than the ordinary coil and
will not give as long a spark as the latter, for the number
of turns of wire are fewer and the potential or voltage
is thereby cut down; but this is more than compensated
for, as the discharge is heavier, caused by a greater
amount of current developed. As the induction coil is,
in nearly every instance, employed to charge a battery
of Leyden jars, the latter discharging its energy by
sparking across the gap, this construction is admirably
adapted to the class of work for which it is designed.

Interrupters. — There are three general types of inter-
rupters used in connection with induction coils; these are
(a) the vibrating spring, (b) the mercury turbine, and
(c) the electrolytic interruptors.

(a) Of the vibrating-spring interruptor there are numer-
ous modifications, but the simplest and most widely
used form is that shown in Fig. 28; it is sometimes

THE APPARATUS OF A COMMERCIAL STATION

termed a Neef hammer interruptor, in honor of Neef , who
invented it. It consists of a steel spring with one end
rigidly atached to a post or standard, while the free
end carries a disk of soft iron called an armature. A
second standard carries a screw having a platinum

Fig. 28. — Vibradiig-Epring Iiilerniptor.

point which makes contact with the vibrating spring
by means of a bit of platinum soldered to the latter.
When a current flows through the interruptor and primary
of the induction coil, the core of the latter is magnetized
and attracts the armature, drawing the spring forward and
breaking the current between the contacts. The core,

50 THE APPARATUS OF A COMMERCIAL STATION

now demagnetized, releases the armature, and the elasticity
of the spring causes it to again make contact with the
stationary point. In this interruptor there is only one
adjustment to make, and this is done by means of the
screw carrying the movable contact-point.

(ft) The mercury turbine interruptor is frequently
used in commercial wireless stations. TJiis device
is capable of making and breaking the primary cur-
rent from lo to 10,000 times per second. Its con-
struction is comparatively simple and its action effective.
In the base of an iron containing vessel having a ribbed
bottom six pounds of pure metallic mercury are placed.
Through the center of the vessel is a revolving worm
or a small centrifugal pump attached to a steel spindle
driven by an electric motor. Above the worm or pump
is a tube or nozzle, also attached to the spindle, and when
the latter is rotated at a high speed the mercury con-
tained in the well is raised until it reaches the nozzle,
when it is projected against the side of the vessel. A
sector or segment of metal sets inside the vessel, from
which it is insulated, and in such a positioii that the
mercury is thrown against it, thus completing the circuit,
and breaks it when it has passed the segment and im-
pinges on the side of the vessel. By varying the speed of
the shaft to which the nozzle is attached, and the length
of the segment, the number of interruptions may be
changed at will. When installed on shipboard, the
interruptor with its motor, which is connected direct to
the spindle, is swung in gimbals, as may be seen in Fig.

Fig. 2g. — Mercury Turbine Intertuptor with Electric Motor.
Mercury InlerrupK-r; E. ElcttriL- Motor' M, Segments; P. Centrilug«li
N. Noasle Pump-, 5, CaBl-iron VbbkL

52 THE APPARATUS OF A COMMERCIAL STATION

29. The motor is an ordinary direct-current machine
wound to operate on the same voltage as the primary of
an induction coil, since both are included in the same
circuit. Where the voltage of the primary is low the
segment must be increased in length; that is to say, for
a potential of no volts the segment must be a quarter
of a circle, and for 55 or 60 volts it must equal the half
of a circle.

(c) Some makers of apparatus prefer the electrolytic
interruptor to the one just described, for in this type there
are no moving parts. The interruptor is made up of
a vessel containing a solution of dilute sulphuric acid,
called the electrolyte, and in this is immersed a platinum
anode, or positive terminal, having a surface of about A
of a square inch, and a lead cathode, or negative terminal,
of 144 square inches. When these electrodes are con-
nected in series with the primary coil and a source of
electromotive force of 40 volts, interruptions will take
place through the formation and collapse of bubbles on
the platinum anode. A picture of this interruptor is
shown in Fig. 30.

The Condenser. — An induction coil if it is to render
efficient service must have an interruptor that "makes"
and "breaks" the current with extreme suddenness; but
even in the mercury-turbine and (electrolytic interruptors
the time required to effect the break is large when com-
pared with zero, i.e., absolute instantaneousness. Where
the source of current, the primary of the coil, and the
interruptor are connected in series the voltage rises in

THE APPARATUS OF A COMMERCIAL STATION

virtue of the inductance of the primary due to the number
of turns of wire of which it is formed, and as a result
of this an excessive spark takes place at the interruptor
contacts.

Kk;. 30. — ^ Elect nil J' lie liitemiplor.

(a) To prevent this a condenser is shunted across the
interruptor where the break occurs. Condensers for this
purpose are made of sheets of tin-foil, these being alter-
nately connected and separated from each other by
sheets of mica. After the condenser is thus built up it
is immersed in" a melted insulating compound under

54 THE ^PPMRATUS OF A COMMERCIAL STATION

pressure and the air is exhausted by means of an air-
pump. This is done to prevent the bubbles of air from
remaining between the successive leaves of tin-foil, which,
if left there, when the condenser is charged might serve
as a conducting path for the energy and so disrupt it.
The Transformer.— While a transformer and an induc-
tion coil are fundamentally the same since both utilize

Fig. 31.— Open Core Transformer.

the principles of mutual induction, a transformer is not
only more simple than an induction coil, but it is also
more reliable and efficient. A transformer may be of
the open-core or closed-core type.

An open-core transformer, Fig. 31, is constructed like
an induction coil- in that it has a long, straight iron core
and around which the primary and secondary coils are
wound, but neither the interruptor nor the condenser
shunted around the latter are needed.

A closed-core transformer. Fig. ^2, has its core formed

THE APPARATUS Of A COMMERCIAL STATION 55

of a ring or a rectangle of iron upon which the primary
and the secondary are wound, but hke the open-core
transformer it is minus the interniptor and the condenser
shunted around it. The open-core transformer is less
efficient than the closed-core transformer and to deliver

Fig. 32. — ^Qosed Cora Transtonner.

an equal amount of energy to the oscillation circuits
as the latter, with the same initial power, more wire and
more insulating material must be used in the former
and this increases its size and weight as well as its cost
of construction.

As an offset to these untoward features the terminals
are widely separated, as compared with a closed-core
transformer, and hence in the former there is less liability

56 THE APPARATUS OF A COMMERCIAL STATION

of the poetential breaking down the insulation and this
obviates the necessity of immersing it in oil. This feature
makes the open-core transformer well adapted for ship
installation as it removes a fire hazard which those respon-
sible for a ship taboo. . In large and efficient land
stations, however, the closed-core transformer is chiefly
used.

Resistance and Impedance Coils. — There are devices
employed for regulating currents supplied to induction
coils and transformers, namely (a) a resistance, and (b) a
reactance. The first is a rheostat formed of a number
of resistance coils and provided with a lever for throw-
ing in the one or more of the coils. A rheostat is
used for induction coils and will serve for small station
sets.

The second is an impedance coil and is formed of a
coil of wire wound on a soft iron core. For large
station sets an impedance coil is more economical
and more efficient than a rheostat.

Spark-gaps. — In some systems the spark-gap con-
sists merely of two brass balls an inch or so in diam-
eter, mounted on brass rods in alignment and sliding
through insulated supports. In others they consist of a
pair of vertical zinc rods with rounded ends, oppositely
disposed, and one of which is movable; these are enclosed
in a circular box having a mica peep-hole and mounted
on top of the form on which the inductance coil is wound
or in any convenient place. The object of enclosing
the spark-gap is to deaden the sound of the disruptive

THE APPARATUS OF A COMMERCIAL STATION 57

discharge, while a view of the spark may be had through
the mica window. Fig. 33 shows the spark-gap with
the case removed.

Fig. 53. — Adjustable Spark-gap.

Fic. 34. — .Adjustable Leyden Jar Condenser.

58 THE APPARATUS OF A COMMERCIAL STATION

L-tension Condensers.^ — There are two types of
high-tension condensers used in wireless transmitters,
namely the Leyden jar battery and the glass plate. The
latter has been generally used, since it is less liable to
breakage than the former.

In either case a condenser is formed by coating the
opposite surfaces of the glass with tin or copper foil.
Such a battery is capable of withstanding high-potential
strains and is inserted in the closed oscillation circuit.
The jars supphed with the sets vary in number from three
to twelve according to the size of the equipments. The
jars are mounted in a case or in a cyUnder their inner
and outer coatings being connected in parallel. Fig. 34
shows a battery of Leyden jars with contact levers for
throwing in and out the jars.

Inductance Coils.^ — In order to tune the open and
closed circuits of a transmitter to the same period of
oscillation, tuning inductance coils are employed.

There are two types of tuning coils in general use,
namely (a) a single coil for conductive coupled circuits, and
ib) an oscillation transformer for inductive coupled circuits.

{a) The single coils are usually formed of four or
more turns of bare copper wire wound spirally on an
insulated frame, or on a hard rubber cylinder. The coil
is fitted with flexible conducting cords with spring clips
attached to their free ends. By means of these clips
the value of inductance may be varied at will. Fig. 35
shows a single tuning coil with the spark-gap moimted
on top.

THE ^PP/iRATUS OF A COMMERCIAL STATION 59

(b) The oscillation transformer consists of two spirally
wound coils mounted in a hard rubber framework. The

Fic. 35- — Variable Tuning Inductance Coil.

lower coil is the primary and the upper coil the secondary
This type of coil permits a large number of wave lengths
to be used and almost any degree of coupling can be

bo THE /IPPAR^TUS OF A COMMERCIAL STATION

obtained. Fig. 36 illustrates a form of oscillation trans-
former.

Aerial Switch. — The purpose of this device, shown in
Fig- 37> is to throw the transmitter and the receptor

Fig. 36. — Tuning Oscillation Transformer.

respectively into and out of connection with the aerial
wire. When the switch is do\vn to send, the power cir-
cuit is closed, and the receptor is cut out. When the lever
is up to receive, the power is cut off and the receptor is
connected with the aerial wire.

THE APPARATUS OF A COMMERCIAL STATION Oi

Anchor Gaps.— These devices are miniature spark-
gaps connected in the aerial wire system and are used

I''iG. 37. — Aerial Swil.li. Fig. 38. — Amhor Cap.

to automatically cut out the transmitter when the re-
ceptor is cut in. One form is pictured in Fig. 38.

Hot-wire Ammeter. — A hot-wire ammeter is connected
the aenal wire and is necessary to show when the sending
circuits are in tune; this ammeter is made to read from
o to 0.5 ampere. It is shown in Fig. 39.

THE APPARATUS OF A COMMERCIAL STATION

CHAPTER IV

APPARATUS OF A COMMERCIAL STATlOlSi— Continued

Receiving Instnunents. — ^There are two types of recep-
tors used in wireless telegraphy; in the first, or coherer
type, the message is printed in the telegraphic code,
and in the second, or auto-detecior type, the message is
audibly indicated by a telephone receiver.

The Coherer Receptor. — This type of receptor has the
advantage of printing the telegraphic code on a paper
tape and hence provides a permanent record of the
received message. It is, however, complicated and there-
fore slow in operation and difficult to keep in adjustment.

In this type of receptor the apparatus comprises (a)
a detector of the coherer type; (6) a tuning inductance
coil; {c) a non-inductive resistance; {d) two fixed con-
densers; {e) a relay; (/) a tapper; {g) a Morse register;
(A) choking coils or polarized cells; {i) dry cells, and
(7) relay testing coils and other instruments.

{a) The Coherer, Fig. 40, consists of a small glass tube
having terminal conductor-plugs of silver, beveled at the
ends to form a V-shaped pocket. Leading-in wires are
sealed in the ends of the tube, and these are attached to the
conductor-plugs as shown. The pocket or space formed

64 APPARATUS OF A COMMERCIAL STATION

by the approaching ends of the plugs contains a small
quantity of nickel and silver filings. The teat projecting

FiC. 40. — Marconi Coherer,

at right angles to the tube is the part where the coherer

was attached to the air-pump and was sealed off after

the tube was partially exhausted,

which prevents the oxidization of the

enclosed filings.

{b) The Tuning Coil consists of
a cylindrical glass tube suitably
mounted with hard rubber ends and
held together with square brass rods;
the latter serve as guides for the
sliding contacts, of which there are
three a3 shown in Fig. 41. Two
of the contact rods are connected
with the lower terminal of the coil.
I The upper terminal of the coil ends in
a binding-post which is joined to
the coherer. The third contact rod
'*'' TuninB ^i!^ ' ^ *^^^^ '" ^ bindlng-post and to this

■ the aerial wire is connected.
(c) Non-inductive Resistance. — ^This is a coil formed of
line wire which has been doubled and wound back on
itself on a spool so that both ends are brought to the outside.

APPARATUS OF A COMMERCIAL STATION 65

This resistance is only used when messages are to be
received from a nearby stition and the received wave
is hkely to be so strong that it will injure the coherer.

{d) Condenser. — In the aerial-wire system between the
coherer and the ground and between the coherer and
the relay a small condenser, built up of sheets of tinfoil
and oiled paper, is inserted. Its purpose is to prevent
tlie atmospheric electricity accumulated by the aerial
wire from passing through the coherer, as well as the
current from tlie dry cell in the coherer circuit from short-
circuiling through the tuning coil to the earth.

Fig. 42. — Polarized Relay.

(e) Relays. — The relay used in ordinary telegraphy is
not nearly sensitive enough for wireless work and hence

60 APPARATUS OF A COMMERCIAL STATION

a polarized relay is used; a polarized relay has a jjer-
manent steel magnet and an electromagnet so arranged
that both poles of the latter are N, or positive, when no
current ilows through the magnet coils. When the coherer
which is connected in series with the coils of the relay and a
dry cell permits the current to complete the circuit, the

Fig. 43. — Marconi Taj^r.

electromagnet is energized and one of the poles changes
its polarity to S, or negative, and the other to increase its
N, or positive, intensity. The armature lever is free to
swing between the poles of the electromagnet within
narrow limits, and when the poles become magnetic the
movable contact-point attached to the armature is drawn
into contact with a stationary point, and in this way

APPARATUS OF A COMMERCIAL STATION 67

closes the circuit in which the tapper and Morse register
are placed. A polarized relay is shown in Fig. 42.

(/) Tappers or Decoherers, — When the filings of a
coherer are drawn together or cohered by the electric
oscillations set up in the resonator circuit and the impulse
printed by the Morse register, there can be no further
indications of the incoming waves until the fihngs are
broken apart or decohered, restoring them to their original
loose state and high resistivity. To accompKsh this it
is only necessary to gently tap the coherer tube. It
would of course be impracticable to do this manually
and so an automatic tapper was devised. The tapper
is very similar in construction to a vibrating electric
bell or the vibrating spring interruptor previously described.
The vibrating armature carrying the hammer is short
compared with that in a bell, and its vibrations are- very
rapid. Attached to the base on which the tapper is
mounted is a holder for the coherer, as in Fig. 43.

{g) Morse Registers. — In th^ two principal foreign sys-
tems that are used in this country the Morse register^
or Morse writer as it is sometimes termed, is used to
print the message on a tape of paper. These registers
are usually constructed to release the spring mechanism,
that draws the tape under the inked disk, automatically,
but in some cases the spring motor is released by the
operator.

A Morse register is shown in Fig. 44 and comprises
the spring motor that moves the paper and the electrically
operated mechanism that print? the dots and dashes

68 ^PPylRATUS OF A COMMERCIAL STATION

upon it. The spring motor is placed inside a brass
case which serves to support the spindles; the case is
fitted with a glass top to keep out the dust and yet enables
the operator to see its various parts. To one of the
spindles projecting outside of the brass case a toothed
wheel serves to draw the paper from the roll under the
inked surface of a steel disk which prints the message

Fig. 44. — Morse Register.

in dots and dashes upon it. The tape should move at a
slow rate of speed compared with the vibrations of the
hammer of the tapper, otherwise there will be a succession
of dots where these should run together and make dashes.
The coils of the register, like those of the tapper, are
wound to about 12 ohms, and the two instruments are
connected in parallel.
(A) Choking Coils and Polarised Cells.—in some

APPARATUS OF A COMMERCIAL STATION 69

receptors choking coils are introduced into the circuits
to cut oflF the local oscillations set up by the sparks
produced on the break of the relay and tapper contacts.
These coils are also wound non-inductively of very fine
silk-covered wire.

In other systems polarized cells are employed instead
of choking-coils to prevent the sparking of the contacts
from affecting the coherer. Polarized cells are small
glass vessels in which a pair of platinum wires are immersed
in a dilute solution of sulphuric acid. A battery of four
or five of these cells is connected across the relay contacts.

(j) Dry Cells, — The dry cells that furnish the current
for operating the relay, tapper, and Morse register are
the ordinary kind used for ringing bells, etc. One cell
is used in the coherer and relay circuit, and four or five
cells, connected in series, make up the battery to operate
the tapper and register circuits. When .fresh the cells
develop about 1.5 volts.

Instruments. — Other than the apparatus described
above there are various instruments sent with each outfit
to facilitate the making of adjustments and insure the
proper working of the equipment.

{a) To ascertain the sensitiveness of the relay a coil
having a total resistance of approximately 40,000 ohms
is sometimes supplied by the makers; this is termed a
relay-testing coil, and besides the end terminals there are
usually two others, so that several values may be obtained.

(6) For tuning the resonator system of the receptor
some kind of a tuning device is necessary; these differ

70 APPARATUS OF A COMMERCIAL STATION

in various makes, but the one shown in Fig. 45 will serve
to indicate the general design. It includes an inductance
coil of the same value as the one used in the receptor, a
condenser having practically the same capacity as that of
the coherer, and a needle-point spark-gap that can be

Fic. 45. — Tuning Device.

adjusted. Its uses and the method of using it, as well as
the other instruments and apparatus described, will be
found in the succeeding chapters.

(c) To test the working properties of the coherer a
lesting-box, or buzzer, is employed. This is a small box of
wood with a buzzer inside. A buzzer is made like an
electric bell, having an electromagnet and a vibrating

APPARATUS Of a commercial station 71

armature but no gong; inside with the buzzer is a dry
cell; these are connected in series with a push-button
projecting through the Ud. When the button is pushed
minute sparks are set up at the contact-points when
the break occurs and miniature trains of electric waves
are sent out in consequence.

Auto-detector Receptors.— Receptors of this type are
extremely simple, easy to keep in adjustment and permit
rapid working. There are several kinds of auto-detectors,
but the magnetic, electrolytic, and crystal detectors are
the most sensitive and consequently the most widely used.
Of the foregoing detectors only the electrolytic requires
a battery current to make it operative, though a small
current can be used to advantage with some crystal
detectors.

Magnetic Detector Receptor. — This receptor has been
adopted by one of the large commercial companies. It
comprises {a) a magnetic detector; {b) a tuning coil;
{c) a variable condenser; and (rf) a pair of head telephone
receivers.

{a) The Detector consists of a small glass tube. Fig. 46,
on which is wound a primary made of a single layer
of wire, the terminals leading to the aerial and earth
wire either directly or through a coupled resonator circuit.
A second coil of wire is slipped over the primary, and the
terminals of this connect with a telephone receiver; two
grooved wheels 4 inches in diameter are connected by
a flexible cord formed of iron wires, which is made to
travel through the glass tube by means of a spring motor

APPAR/iTUS OF A COMMERCIAL STATION

enclosed in a case, while two steel horseshoe magnets
are placed closely to the moving band of wire and adjusted
until the maximum effect is obtained.

•1
n
o

(-»■

«-»■

To Ground Wire

^ ^ o

o cr ^
o ^ a>

"« CD

Aerial Wire

{b) Tuning Coil, — For this receptor the tuning coil con-
sists of silk-covered magnet wire wound on a glass form.
It is provided with a pair of sliding contacts as shown
in the accompanying illustration, Fig. 47.

APPy4IUTUS OF A COMMERCIAL STATION 73

the rotary variable type and is built up of a lai^e number
of semicircular brass plates, half of which are fixed and

Fig. 47.— Two-slide Tuning Coil."^
half of which are rotary, the clearance between them
being a"! inch. These plates are contained in a brass

Fig. 48. — Variable Receiving Condenser.

case with a hard-rubber handle on top for making the
adjustments.

74 APP/IR/iTUS OF A COMMERCIAL STATION

(d) Telephone Receivers. — The telephone receivers used
in connection with auto-detector receptors are gei,erally
of ^the watch-case type. The ear-pieces are connected
to a band of spring steel which holds them comfortably
on the head and closely to the ears; hence this form

Fig. 4g. — Adjustable Head Telephone Receiver.

is known as a head telephone receiver. It is shown
in Fig. 49.

Crystal Detector Receptors. — This type of receptor is
largely used in the Army and in the Navy. It is formed
of {a) a crystal detector; (b) a tuning coil; (c) a variable
condenser, and {d) a pair of head telephone receivers.

Crystal Detectors. — There are many crystals which,
when placed in light contact with some of the metals
or with other crystab, will serve as a detector of electric
waves. Carborundum, silicon, chalcopyrite, zincite, and
iron pjrites are a few of the most important crystal

APPARATUS OF A COMMERCIAL STATION

used, while iron, phosphor bronze, tellurium, aluminum,
and molybdenum are some of the metals employed.
Zincite in contact with chalcopyrite forms what is known
as the perikon detector.

These elements are held in position in a metal frame,
having a variable contact. A good holder is shown in

Rotating Holder

Fig. so.— Crystal Detector.

Fig. 50. It consists of two brass standards mounted
on a hard-rubber base. Through the shortest standard
a rotatable disk is pivoted; this
disk carries four brass shells
into each of which a crystal is
set in lead.

Passing through the opposite
standard is a brass rod carrying on its inner end a crystal
holder which in this case is secured by a set screw;
the outer end of the rod is fitted with adjusting

Fic. 51. — Filed Condenser.

76 APPARATUS OF A COMMERCIAL STATION

screws which permits the lightest contact of the opposing
crystals to be made.

Fioced Condenser. — A small mica and tin-foil condenser
of fixed value is used to prevent the direct currents
set up in the detector from flowing through the inductance.

It is shown in Fig. 51.

Tuning Coil, Variable . Condenser, and Telephone Re-
ceivers. — These ' are identical with those described in
connection with the magnetic detector receptor. It is
necessary to use a high-resistance telephone receiver in
connection with a crystal detector and such receivers are
usually wound to 2000 or 3000 ohms resistance.

Electrolytic Detector Receptor. — A receptor using an
electrolytic detector is more sensitive than either of the
foregoing types, but it is also more difficult to keep in
adjustment. A receptor of this type may be made up
of {a) an electrolytic detector; {b) a tuning transformer;
(c) a variable condenser; {d) a potentiometer; {e) a dry
cell, and (/) a pair of head telephone receivers.

The electrolytic detector. Fig. 52, is not unlike the
electrolytic interrupter previously described, though on
an exceedingly small scale. Into a small platinum
vessel a little larger than the end of an unsharpened
lead pencil, and which forms the cathode or negative
terminal, a very fine platinum wire a few thousandths of
an inch in diameter is just immersed in the solution
or electrolyte; of the latter there are several different
kinds, as (fl) a 10 per cent solution of sulphuric acid;
(6) a dilute alkaline solution; and {c) a 20 per cent

APPARATUS OF A COMMERCIAL STATION 77

solution of nitric acid. The points are made of a silver-
jacketed platinum wire, the finest obtainable being .00002

Fig. $2. — Electrolytic Detector.
inch in diameter. The detector is provided with a screw
adjustment for raising or lowering the fine platinum point
in the electrolyte.

78 APPARATUS OF A COMMERCIAL STATION

Oscillation Transformers. — Tuners of the transformer
type, Fig. 53, are used in inductive coupled receptors
and are fonned of two coils of wire, one sliding inside the
other. Both coib are provided with mechanically oper-.

Fig. S3. — Tuning Oscillation Translnrmer.

ated sliding contacts whose positions are varied by hard-
rubber handles.

Condensers and Telephone Receivers. — These instru-
ments are the same as those described for use with the
electrolytic detector receptor.

CHAPTER V
THE AERIAL-WIRE SYSTEM

The Signaling Distance. — The aerial-wire system is
understood to include an oscillation circuit from the top
of the wire to the plate in the ground and hence com-
prises the aerial wire, the spark-gap, or detector, where a
simple open circuit is used, or an inductance coil, where
a compound, i.e., an open and a closed circuit are coupled
together.

The successful transmission of wireless messages depends
largely upon the condition of the aerial-wire system, and
the operator, if he wishes to obtain the best results, must
not overlook the necessity of keeping them perfectly
insulated from the mast, building, and trees. It is not
enough to know that the wires have been put up properly,
for moisture may collect upon the suspension insulator
that joins the top of the wire to the tail-block; and if
this occurs and is not attended to, much of the energy other-
wise available for radiation is lost. For this reason the
aerial wire should be arranged with a tail-block on the
cross-tree or topgallant-mast so that it may be lowered
for inspection and hoisted up again.

8o THE AERIALIVIRE SYSTEM

The distance to which the waves may be radiated
depends on several factors, such as the initial energy or
amount of power used, whether the transmission is to take
place over salt water or the surface of the ground, the kind
of system used, the height, form, and dimensions of the
aerial, etc. Roughly it may be said that, with a given
amount of power, instruments of standard make, and all
other things being assumed equal, the distance to which
signals can be sent increases as the square of the length of
the aerial wire that sends out the waves; or in other
words, if the wire is 20 feet in height and will send mes-
sages one mile, then a wire 40 feet in height will send
them four miles, and one 80 feet in height will carry
waves 16 miles, and so on. This deduction holds good
only in the case of a single-wire aerial, for where the
aerial is formed of more than one wire, or carries a cage
at the top or other capacities at its lower end, the arrange-
ment permits a greater amount of energy to be radiated
and the law is no longer teaable.

Electric waves are propagated to much longer distances
over the surface of salt water than over fresh water,
snow, or land. Considerable difference in the signaling
distance is found to exist due to the condition of the
weather as well as to the different seasons of the year, as,
for instance, it may be cited that the effective range is
cut down during the heated period of the summer months.
A marked difference is also noticed according to whether
the messages are sent during the day or night, the longest
distance being attained after the sun has gone down.

THE AERML-IVIRE SYSTEM 8r

This effect is attributed to the dissipating influence of
daylight on the oscillating currents set up in the aerial
wires.

The Aerial Wire. — ^The term aerial wire is used to
designate the wire or wires leading from the instruments
in the operating-room to the masthead outside which
supports it. The aerial may be formed of one or more
wires, those generally used being made of phosphor-
bronze and having a diameter of about A of an inch.
As we have seen, the length of the aerial wire, where this
is single, determines the wave-length to be sent out; in
some installations two aerial wires are used, and these
arc connected together, usually through the medium of
a small spark-gap, at the bottom before they enter the
station. Other systems employ aerials that are con-
nected to wire cages at the upper end which increases
their capacity, and they not only send out a longer wave
but waves of greater power. Where an aerial is formed
of a number of wires these should be arranged at a goodly
distance from each other, for unless this is done their
combined capacity will not be multiplied by their indi-
vidual capacities.

The distance over which it is possible to send will
depend, as wc have seen, on the length and the number
of wires of the aerial, as well as on the amount of current
the induction coil is capable of delivering to the oscilla-
tion circuits. The capacity of an aerial wire system is
of the utmost value in transmitting, for upon this depends
the amount of energy radiated. In receiving, however,

82 THE AERML-iyiRE SYSTEM

large capacity aerials are not needed, and it is often well;
when more than one wire forms the aerial to cut one or
more of them out, especially if they are provided with
cages.

Types of Aerials. — There are several types of aerial
wire systems and among the more common may be cited
{a) the straight vertical aerial, {h) the obliqiie aerial, (c)
the rwrizontal, fiat-top, or T, aerial, and {d) the umbrella
aerial,

(a) In the early days of wireless the aerial consisted
of a single wire suspended vertically from the spar of a
masthead. As the art progressed it was found that a
metal plate connected with the upper terminal of the
wire gave better results since it added greater capacity
to the aerial wire system.

(b) Due to the necessity of keeping the aerial wire clear
of the mast it became common practice to stretch it at
an angle as shown in Fig. 54, thus giving rise to the
obliqtce aerial. Ascertaining that added capacity permitted
a greater signaling distance to be obtained more wires
were added to the aerial, a cylindrical cage of wires
usually being connected in at the top. Adding such
capacities is electrically equivalent to increasing the length
of the aerial.

(c) The next development was the horizontal, flat-top,
or T aerial, and as this type offered a convenient means
of obtaining a large capacity and of keeping the aerial
clear of all obstructions, especially on board ship, it
found instant favor. In this construction the number

t tSe New York Navy
83

THE AERIAL-IVIRE SYSTEM

of parallel wires may be placed as far apart as desired,
a decided advantage, as this permits the greatest capacity
with the smallest inductance to be obtained, which are
essential factors for securing the highest efficiency.

Fig. 55 shows the arrangement of a T aerial and Fig.
57 illustrates the aerial installed on the Imperator,
It consists of two stranded phosphor-bronze wires held
apart by two lo-foot spreaders. Two vertical wires

Fig. ss.—T Aerial.

connect with the horizontal wires in the middle and
the former lead in to the operating room on the upper
deck. The aerial is suspended between the tops of the
two masts 216 feet above the sea and has a length over
all of 290 feet.

{d) From the T aerial to the umbrella aerial was but
a step farther in the evolution of aerials. The latter
type consists of a number of wires forming a cone, the
apex being the top of a mast with the wires branching
out in all directions at the head. Since the individual
wires are kept well away from each other this arrangement
gives the majdmum capacity, and hence this aerial is

86 THE AERIAL-IVIRE SYSTEM

the most efficient known. Aerials of this type are largely
used in the portable sets of the United States Army.
Fig. 56 indicates the arrangement of the wires in an

Fig. 56. — Umbrella Aerial.

umbrella aerial and Fig. 58 shows it supported by a jointed
pole.

The Mast.* — In fitting a ship with wireless apparatus
the masts -are generally high enough to serve to sustain
the aerial wire; on shore the mast may be of any height,
and this depends to some extent on the distance to be
covered; masts are seldom less than 90 feet in height
or more than 210 feet. When this height is reached
and it is desired to signal farther the electrical dimensions
of the aerials must be increased by adding more wires and
by installing a transmitter of greater power. It is not de-
sirable to make the mast of iron or steel, as some of the
energy of the electric oscillations set up in the aerial is
absorbed by the mass of metal and the radiation is cut
down in consequence. The masts are best made of good,
clear pine and may be built up of three or four sticks; three
sections are ample if the masj: does not exceed a height of
180 feet, which is the highest used in the United States
Navy, the lowest approximating 130 feet. The mast

Fig. 57.— T Aerial on S. S. Imperator.

Fig. s8.— Portable Umbrella Aerial.

THE AERML- IV IRE S YS TEM 9 1

should be supported by two sets of rigging, that of the
lower mast being of wire cable and that of the topgallant-
mast of hemp rope.

One of the requirements to insure good transmission
is to keep the mast well away from structures of all kinds,
and wherever possible there should be no obstructions'
between the sendbg and receiving stations; of course
this is not practicable in signaling over land, and the
distance is therefore very much cut down when com-
pared with telegraphy over the sea, where the line of
propagation is clear. In the U. S. Navy the mast on
shipboard from which the aerial wire is suspended is
required to be not less than 130 feet above load-water-
line, and the rigging of all the mast-poles is set up with
hemp rope instead of wire, as well as all the other rigging
of the ship, so that there will be as little absorption of
energy as possible.

In commercial systems the height of the mast is often
less or more than that specified by the Navy. A mast
of 190 to 210 feet is best constructed of four poles set
in cross-trees and supported by fids, or bars of iron with
a shoulder at one end to sustain the topmast over the
head of the lower mast; the mast is guyed to braces, and
these, if on a sandy seacoast, must be sunk from fifteen
to twenty feet deep. The guys may be of hemp or wire
rope with hemp terminals spliced in about 100 feet from
the ground; the purpose of combining the wire with hemp
is to provide proper insulation for the aerial. wires, which
are supported by a cross-tree near the top, holding them

92 THE AER14L-IVIRE SYSTEM

out so that they cannot come in contact with the
guys.

Portable Mast. — The portable mast, Fig. 58, used
by the Signal Corps of the U. S. Army consists of twelve
hollow wood sections, each 6.8 feet long, nine sections
constituting the mast proper and three sections serving

Fic, 59.— Umbrella Aerial and Jointed Mast Packed for Transportation.

as a raising lever, the sections fitting into each other.
From the metal part of the top section extend six stranded
phosphor bronze aerial wires, each of which are provided
with snap hooks at one end, the other end terminating
in a hard-rubber insulator.

On erecting the mast the sections are put together on
the ground. Guy lines are attached to aid the raising
of tht: mast. The mast is then revolved on its horizontal

THE AERIAL-IVIRE SYSTEM 93

axis until the lever sections are in a vertical position. In
the usual field operations four men can quickly and
safely raise the mast under all ordinary weather condi-
tions. When the mast is taken down it is easily trans-
portable on the back of a mule as pictured in Fig. 59.

Methods of Suspension. — Where the aerial wires are
attached to the cross-tree of the topgallant -mast it must
be well insulated. A simple method for suspending
aerial wires is shown in Fig. 60; the mast, topgallant-
spar, the insulator, aerial wire and its cage are all named
in the drawing, so that it will be readily understood when
it is said that the insulator, which is of heavy glass or
porcelain, is attached to the spar by a loop of tarred
rope running through its center. The upper end of
the wire to which the cage is made fast is turned over
the outside of the insulator, having a groove cut in it,
and twisted fast.

A better suspension than the foregoing and one
that has been adopted by various commercial companies
is shown in Fig. 61. In this case corrugated strain in-
sulators formed of heat, water and smoke-resisting com-
position are used. The larger ones are about 2 inches in
diameter and a foot in length, and the smaller ones are
about 3 inches in diameter and 4 inches in length.

The aerial is constructed by twisting each wire to a
small strain insulator which in turn is secured to the wood
spreader with a withe. One end of the long insulator
is wired to the ends of the spreader with small steel
cables while a hemp rope running through a tail block,

THE AERI/IL-IVIRE SYSTEM

3
i/i

The Insulator

Fig. 6o. — ^A Simple Method of Suspension.

THE AERl/IL-lVIRE SYSTEM

the latter being fixed to the mast head, is spliced to the
opposite end of the insulator. Fig. 62 shows the long
strain insulator to better advantage.

co;f^44t«iiiiiiiiiiiiiiiiiiiittm^^*^^

Fig. 62. — ^Long Strain Insulator.

A method to prevent leakage where the aerial wire
leads in the station from the mast to the instruments is
shown in Fig. 63, the rattail, or leading-in wire, passing
through a composition or hard-rubber bushing inserted
in a hole cut in the center of the window pane.

The leading-in insulator shown in Fig. 64 is largely

96 THE AERIAL-IVIRE SYSTEM

used in the installations of the U. S. Navy as well as by
some of the commercial companies. It is made of a
compositioftr called electrose, and is better than hard

Fig. 63. — Leading- in Method.

rubber, for it docs not shrink, resists smoke and is not
affected by water.

The Grounded Terminal. — A good ground is quite as
essential to the successful operation of a wireless system
as a good aerial. Sheets of copper or zinc, preferably

THE /tERIylL-IVIfiE SYSTEM 97

the former, are embedded in damp earth, and this forms
a very good earth connection. A shore station set of
instruments should have from loo to 150 square feet of
such surface buried deeply enough to insure a permanently
damp connection between the soil and the plates of metal.
Copper usually comes in rolls having a width of about
2 feet, and a sufficient number of rolls of the heaviest
copper or zinc should be connected together by strips
5 or 6 inches wide cut from the plates and soldering the
latter securely together. From the different plates form-

FlC, 64. — Electrose Leading-in Insulator.

ing the ground similar strips are soldered, and these
are led up to the surface, where they are connected to-
gether and then to a wire leading to the instruments.
Sometimes the plates are set in the ground vertically,
though more often they are placed horizontally; but
this is largely a matter of choice modifiable by condi-
tions, and it makes little difference so long as they are
well grounded. Frequently places will be found where
it is not possible to obtain a good ground, and in such
cases a larger amount of surface is necessary, and a
switch can be arranged between the grounded plate and
the receiver so that the detector may be cut out entirely

9S THE /iFRIAL'lVIRE SYSTEM

when sending; where a good ground cannot be had it has
been found an excellent plan to provide the transmitter
and receptor with separate ground plates. The difficulties
of finding a good ground is not encountered on board
ship, for all that is necessary is to simply connect the
ground terminal to the nearest pipe or other piece of
metal connected with the hull of the ship.

The Operating Room. — In this room the apparatus
is installed and operated; it may be of any size, though
preferably isolated from everything else, and it should
have not less than 40 or 50 square feet of floor surface.
On shore, small buildings of convenient size and location
are often put up expressly for the purpose; the operating
room should be in a line with the aerial and the
grounded plates should be embedded as closely to the
room as may be convenient. A well-designed oper-
ating room especially built should have windows on
three sides and not only be well lighted, but venti-
lated and kept perfectly dry. Through the window
nearest the mast a hole for the aerial leading-ih wire
must be cut, as previously described. Fig. 65 shows
the New York Navy Yard station. When the appa-
ratus is installed on board ship the best place for
the operating-room is between the upper deck and
the next one below, the rat-tail of the aerial wire passing
through insulators of composition or hard rubber in the
upper deck. The instruments should be mounted on a
rigid bench, the height of an ordinary table, and this
may extend from one end of the room to the other, if the

O to

THE /lERML'lVIRE SYSTEM loi

room is not too large; a couple of drawers beneath the
table will be found handy for tools, extra parts, etc.
The current for shore stations is obtained whenever pos-
sible from the regular mains at no volts pressure, but
often the station is located in some isolated and inaccessible
place where there is no central station, and here a small
gasoline or oil engine coupled to a direct-current dynamo
generating looo to 2000 watts supplies the initial energy.
Such units should be installed in a separate house, at
least 100 feet from the operating-room, so that the noise
of the engine will be muffled — a desirable feature always,
but an absolute necessity where the receptor is of the
auto-detector type. Right here I may say that the young
man who expects to become a proficient wireless operator
should read ud and become familiar with the construe-
tion of small gasoline and oil engines and dynamos.

Aerial Wires and Grounds for Field Work. — Under
certain conditions of warfare and for experimental pur-
poses, balloons and kites may be used to raise the aerial
wire. The balloons used are small silk bags inflated
with hydrogen gas; these are sent up when there is not
enough breeze to elevate a kite. The aerial wire is
usually a single, bare No. 14 stranded aluminum, steel, or
copper wire 500 or 1000 feet in length and serves not
only as an aerial wire, but in the place of the kite string
as well. In light . breezes the tailless kite known as a
Malay or Eddy kite is used, an idea of which may be
gained from Fig. 66; a Blue Hill box-kite is designed to
fly in a wind having a velocity of 30 or 40 miles per hour;

I02

THE AERUL-IVIRE SYSTEM

it is shown in Fig. 67. The aerial wire may be attached
directly to the string of the kite after it is started and up

in the air a few feet. These kites are fitted with a bridle
having a loop to which the kite-string is attached. The

•- t J- «' «.

c c

THE AERlA-iVIRE SYSTEM 103

aerial and ground cables are provided with plugs to plug
into tlie aerial switch and to the ground connection of
the coil.
The grounded terminals of field outfits are seldom em-

Fio. 67.— IJluc Hill Box-kite.

bedded in the earth; the terminal wire or cable is attached
to a roil of wire netting, like that used for chicken fences,
and this is spread out evenly on the ground or dropped
into water, if there is any; or what is just as good is to
spread the netting out on a grassy plot, which provides

I04 THE AERIAL'IVIRE SYSTEM

an excellent earth, for grass and other growmg vegetation
are conductors of electicity, and as the meshes of the wire
net come in contact with the thousands of blades of
grass, and these in turn have roots in the damp soil
underneath, a fairly good ground is assured.

CHAPTER VI

WIRING DIAGRAMS FOR TRANSMITTERS

Wiring Diagrams. — It is not often that an operator,
especially if he is a beginner, is called upon to under-
take the installation of a wireless set unless it is under
the direction of an experienced man "higher up." In
commercial companies the experts selected for this impor-
tant work are chosen as a rule from the ranks of the
operators, the preference naturally being given to those
who have shown a special aptitude for this class of work.
In the United States Navy wireless telegraphy is under
the supervision of the Bureau of Equipment, and officers
versed in this branch of the art look after the installations
of different ship and shore stations, while in the Army
it is attended to by the Signal Corps and likewise in
charge of competent officers.

It will be found useful, however, for the operator to
know how the instruments are wired, and a necessity to
understand their connections; but without a wiring
diagram of the specific form of apparatus he is working

105

io6 IvmiNG DIAGRAMS FOR TRANSMITTERS

with, the novice would be lost in the maze of wires about
him if he were given charge of a station. When a begin-
ner accepts his first position, or an operator goes from
one company to another, he will, it is safe to say, receive
some instruction relative to the station he is to have
charge of, and this may continue until he becomes per-
fectly familiar with the apparatus installed. By study-
ing the wiring diagrams to follow, the operator will have
little difficulty in tracing out the connections of any
system he may be called upon to work. As to the placing
of the apparatus on the operating table there is no hard-
and-fast rule to be adhered to, but on the other hand the
operator must use his best judgment arrd meet the cir-
cumstances in the most practical way. The key may
conveniently be placed about the middle of the table,
with the transmitting apparatus on the left-hand side
and the receiving apparatus on the right-hand side.
In shore stations there is more room, but it is doubtful
if this is of any material advantage, for it is well to have
the apparatus set up so that it forms a compact unit,
since then every part is under the immediate and con-
stant observation of the operator.

Wiring Diagram of an Ordinary Induction Coil, In-
terrupter and Condenser. — Where an ordinary induction
coil is employed in sending, the spring interruptor is
mounted on the same base, at the end of the coil, and
the condenser is placed in the base, which is made hollow
to receive it. By referring to the diagram Fig. 68 it will

IVm/NG DIAGRAMS FOR TRANSMITTERS

107

be seen that one terminal of the primary of the induction
coil leads direct to one of the binding-posts, placed on
the outside and ,end of the base; the other terminal of
the primary coil is connected to the fixed end of the
vibrating spring; the current is completed through the
adjusting screw and its support, which is connected to

Core of Coil

Armature

^^^1 I Adjusting Screw

Battery

ji|i|i|ih]^

Fig. 68. — Wiring Diagram of Induction Coil, Tnterruptor, and Con-
denser. Dotted Lines Show Base of Coil.

the opposite binding post, also on the outside. Shunted
around the spring and the adjustable screw is the con-
denser. The wiring, in so far as possible, is concealed
in the base of the coil, leaving the binding posts only
exposed, and to these are attached the key and the
batterv.

Wiring Diagram of Induction Coil with Independent
Spring Interrupter. — ^While in the improved type of
induction coil the spring interruptor is generally mounted

io8

IVIRING DIAGRAMS FOR TRANSMITTERS

on the base with it, it is also occasionally mounted sepa-
rately, this being possible since its action does not depend
on the magnetization and demagnetization of the core

Core

Primary Coil

Condenser

To Battery

Fig. 69. — Wiring Diagram of Induction Coil with Independent

Interruptor.

of the coil. The independent interruptor is provided
with two sets of make-and-break contacts, the first formed
of heavy platinum wire and placed in the main circuit, as
indicated in Fig. 69 by the heavy lines, and the second

IVIRING DIAGRAMS FOR TRANSMITTERS 109

of lighter platinum points, as shown by the light lines.
Following the heavy lines it will be seen that the battery
or other source of electromotive force is connected on
one side to one terminal of the induction coil, its opposite
end leading to the heavy platinum movable contact
attached to the upper part of the stiff est of the two springs;
when the spring is in its normal position, namely, when
there is no current flowing through the circuit, it makes
contact with the heavy platinum stationary contact-
point which is connected to the battery. Under these
conditions the smaller contacts in the shunt circuit are
also in contact; thus both the main circuit through the
primary of the induction coil and the shunt circuit through
the electromagnet are closed in so far as the contact-
points arc concerned, but open through the key. When
the circuits are closed by means of the key the current
flows through the shunt as well as the main circuit and
hence energizes the coil and the electromagnet, when the
latter breaks both circuits by attracting the armature
carried by the spring on which are attached the movable
contacts. The condenser, frequently an adjustable one
and mounted in a separate box, is shunted across the
main contact-points as shown.

Wiring Diagram of Induction Coil with Mercury
Turbine Interrupter. — Where a mercury turbine inter-
ruptor is used it is connected in series with the primary
coil, the key, and the source of current, as in a simple
spring interruptor. A condenser is shunted around the
interruptor in the same manner. Since a small motor

fVIRlNG DIAGRAMS FOR TRANSMITTERS

is required to rotate the interrupter, a circuit is led off
from the main line to the motor, while a variable resistance
or rheostat is inserted to regulate the current, all of
which is shown in Fig. 70.

To Dynamo

_ToDynamo

Key

Mercury
Interrupter

AAAA/

Variable Resist.

*— O

Motor

Fig. 70. — Wiring Diagram with Mercury Turbine Interrupter.

An Induction Coil with Electrolytic Interrupter,— Where

an electrolytic interruptor is used it is connected
in series with the primary coil, the key, and the source
of current, as in a simple vibrating-spring interruptor.
Since an electrolytic interruptor has a small inherent
capacity of its own, it is not absolutely necessary to use
a condenser shunted around it, but a small condenser can
be used to some advantage.

Keys. — ^As previously stated in Chapter IV, some
systems of wireless telegraphy provide keys with con-

IVIRING DIy4GRAMS'FOR TRANSMITTERS

III

densers to cut down the sparking at the contact-points;
many are furnished with magnetic blowouts, and again
in others the break takes place under oil.

{a) Where a condenser is used it is shunted around
the contact-points of the key just as in the case of the
interruptor, and as the condenser is in the base of the

To Dynamo

Polar Projection

Key

Polar Projection

To Coil

Fig. 71. — Connections of Key and Magnetic Blowout.

key, the connections are always made when the key is
assembled.

{b) This latter statement is also true where a magnetic
blowout is used, but since new phenomena are involved
the above diagram, Fig. 71, may prove of value. It
will be observed that the coils of the magnets, the polar
projections of which are oppositely disposed at right angles
to the contacts of the key, are connected in series with

112 HAIRING DIAGRAMS FOR TRANSMITTERS

the key, coil, and source of energy. The diagrammatic
sketch of the circuit shows the actual position of the
magnets, the contacts of the key, and the connections.

(c) Keys whose contacts break in oil are connected in
series with the primary and source of energy, as in the
two preceding cases.

Diagram of a Simple Induction Coil Transmitter. —
The diagram, Fig. i, Chapter I, shows a simple open
circuit transmitter using an induction coil with a vibrat-
ing interruptor.

Diagram of a Simple Transformer Transmitter. — In-
stead of the induction coil excited by direct current a
transformer of the open or closed core type may be
employed to energize the aerial-wire system. There may
be cited three reasons for the use of this arrangement,
namely: (i) there are places where only alternating
current is available; (2) the interruptor of the direct-
current induction coil, which is sometimes a very trouble-
some device, is done away with; and (3) larger amounts
of energy may be transformed from the initial current
into electric oscillations. A transmitting system of
this kind in its simplest form is shown in Fig. 72, and a
reference to the diagram will make the connections clear;
the mains of an alternating-current generator connect
with the primary of the transformer through the medium
of a pair of choke coils, the latter being made like those
described on page 68 except that they are larger and
better insulated. The secondary of the transformer is
connected to the spark-gap as in the case of an ordinary

fVIRING DIAGRAMS FOR TRANSMITTERS

p
3

3
P

H
p

3
in

^ 'illl

Alternating Current
Generator

Transfornner

with closed
Magnetic Circuit

Secondary

Spark-Gap

O O-

Leyden Jar Battery

Aerial

114 IVIRING DIAGRAMS FOR TRANSMITTERS

induction coil and a battery of Leyden jars in parallel
with the spark-gap as shown. The aerial wire is con-
nected to one side of the spark-gap, and the grounded wire
to the opposite side. In tuned transmitters using alter-
nating current, the secondary coil of the transformer,
Leyden -jar battery, and inductance coil are connected as
in the diagram Fig. 73 or 74.

Diagram of the Primary or Low Tension Circuits. —
The wiring of the primary circuits of an induction coil
and a transformer transmitter is well brought out in
the diagrams Figs. 70 and 72. Some details are lacking,
but these are suppUed and will be found in the diagram
showing the complete transmitter.

Diagram of Conductive Coupled Oscillation Circuits. —
This is the simplest type of tuned transmitter. The
terminals of the secondary coil are connected with
the spark -balls forming the gap through which the spark
takes place. From one of the spark-balls a wire leads
to the inner coatings of the battery of Leyden jars, these
being connected in parallel by means of chains and
plugs. The outer coatings of the Leyden jars, also in
parallel, are connected to the aerial wire through a cut-
out spark-gap, as shown in Fig. 73; the lower end of the
aerial is connected with the earth through the inductance
coil by means of a flexible wire ending in a plug or spring
contact. A transmitter having its open and closed
oscillation circuits connected in this manner is termed a
direct or conductive coupled system and is of course a
compound system.

IVIRING DIAGRAMS FOR TRANSMITTERS ' 1 5

Diagram of InductiTe Coupled OsciUation Circuits.—
.Another method of coupling oscillation circuits much in
favor at present is shown in Fig. 74; here the secondary
of the induction coil connects with the spark-gap and

^Ground
Fig. 73.— Wiring Diagrams of High Tension Close Coupled Circuits.

the opposite end of the earth. The purpose of
interposing this transformer is so that the potential of
the oscillations set up in the closed circuit may be in-
creased in the open circuit.

IVIRINC DIAGRAMS FOR TRANSMfTTERS

Wiring Diagram of a Complete Telefunken Trans-
mitter.— A complete transmitting apparatus such as is

Fig, 74. — Diagram of Loose Coupled Transmitter.

largely used in the United States is shown in Fig. 75.
It is a combination of the primary circuits Fig. 70 and
the secondary circuits Fig. 73 coupled together and with

WIRING DIAGRAMS FOR TRANSMITTERS

117

all the details of the system added. Following the
primary circuit from the mains it will be seen that one

1103 doue^onpui

leuay

side leads to a rheostat, for regulating the current flow-
ing through the primary coil and interruptor, thence the

ii8 IVIRING DIAGRAMS FOR TRANSMITTERS

circuit continues through the primary, the interruptor,
the key, the blowout magnet coils, and to the fixed con-
tact of the aerial switch. From the other fixed contact
of the aerial switch the circuit leads back to the mains,
as shown by the heavy lines. A second circuit is derived
from the main circuit, and this conducts the current
to the motor for rotating the turbine interruptor, these
being connected by a belt illustrated by the dotted lines.
Interposed in this circuit is a rheostat for controlling
the speed of the motor. The secondary of the coil is
connected with the spark-gap, and in parallel with the
latter is the Leyden-jar battery and the variable inductance
coil with its flexible conductors.

From a point between the Leyden-jar battery and the
inductance coil a wire connects with the aerial, though
the open circuit is broken by the spark-gap cut-out, the
purpose of which is to prevent the impressed oscillations
set up in the aerial when receiving from flowing through
the transmitter. On the other hand the minute spark-gap
does not prevent the oscillations set up by the transmitter
from surging through the system.

Diagram of a Complete Marconi Transmitter. In
the Marconi system as now installed on Atlantic liners
the transmitter comprises an induction coil giving a
lo-inch spark and provided with a simple spring inter-
ruptor moimted on the base with the coil and operated
by the core of the latter, or an alternating current trans-
former developing 25,000 volts at the terminals of its
secondary. In either case the source of energy is taken

fflRlNC DIAGRAMS FOR TRANSMITTERS 119

from the mains of the ship's generating unit. The primary
circuit includes a primary coil, a key, and the source

5 I
I \

JCW

of energy. The terminals of the secondary coil lead to a
spark-gap, and in parallel with this circuit are connected

I20 IVIRING DIAGRAMS FOR TRANSMITTERS

in an inductance coil and a battery of Leyden-jars, the
outer coatings leading to one side of the spark-gap and
the inner coatings to one terminal of the inductance coil.
There are twelve of the jars, and a switch is arranged
on top; the three jars on either end may be cut in or
out according to the capacity desired. The inductance
coil forms the primary of a high-tension transformer
the secondary of which connects the aerial with the
ground terminal. In this system the inductance coil is
not woimd around the Leyden-jars, but the transformer
is mounted in a case and attached to the wall. The
wiring diagram is shown in Fig. 76.

CHAPTER VII
WIRING DIAGRAMS FOR RECEPTORS

Circuit Connections. — In order to master with the
least difficulty the various connections of a wireless
telegraph receptor, the student should bear in mind
that the receiving devices, like those of the transmitter,
may be divided into two general classes, namely, those
that are not tuned and those that are tuned, or in other
words into simple open circuit resonators and those
having compound systems. These systems may again
be subdivided into those that use detectors of the coherer
type in conjunction with relays and Morse registers,
and those that use auto-detectors of the electrolytic,
magnetic and crystal types in combination with telephone
receivers.

The wiring of a simple open circuit resonator is fixed
in its arrangements, and there is nothing for the operator
to adjust except the relay and instruments in the low-
voltage or internal circuits. This style of equipment is
very seldom found in use, unless in some antiquated
station, but an understanding of its connections will
enable the beginner to grasp the more complex systems

121

122 IVIRING DIAGRAMS FOR RECEPTORS

of tuned receptors, even as it furnished in the earlicr
history of the art a stepping stone for the improvements
that have resulted in tuning as we know it to-day. Those
receptors in which tuned resonators, as the aerial wire
system of receptors are termed, may employ either
a detector of the coherer type with a relay and a
Morse register in the internal circuit, or an auto-detector
and telephone receiver, depending on the make of appa-
ratus installed and the class of work they are intended
for. The auto-detector receptor has practically super-
seded the coherer receptor for all classes of work.

Diagram of a Simple Open-circuit Resonator. —
Since the received waves are transformed into electric
oscillations in the receiving aerial, before there can be any
electrical manifestations in the local circuit the aerial
and grounded wire must be connected directly or indirectly
to the detector. Where the aerial wire is connected
directly to one side of the coherer and the ground -wire
to the opposite side, as in Fig. 77, the resonator system
cannot be tuned to the length of the wave received and
much of the energy is thereby wasted. Systems utilizing
simple open-circuit radiators and resonators have been
entirely supplanted by tuned apparatus for all commercial
installations.

Elementary Diagram of the Detector and Cell Circuit.
— In order that the effects of the oscillations set up in
the aerial wire system may be translated into the alpha-
betic code and perceived either visually or audibly an
internal circuit is provided by connecting a detector, a

PyiRlNG DIAGRAMS FOR RECEPTORS.

123

dry cell, and some kind of an indicating device, such as
a galvanometer, a telephone receiver, or a relay working
a register as shown in Fig. 78, assuming that the resona-

Detector

05
LU

Ground ^^=

Fig. 77. — Simple Open Circuit Resonator.

tor system used is of the simple open-circuit type above
described. That all of the energy of the oscillations may
be impressed on the coherer, non-inductive resistances,
or choke-coils as they are called, or polarization -cells,
are usually inserted in the internal circuit to prevent

124

IVIRING DIAGR/IMS FOR RECEPTORS

the oscillations from surging through the instruments
which oflfer a path of less resistance.

Diagram of a Conductive-coupled Resonator. — ^The
general diagram, Fig. 79, is of a compound-circuit resonator

Detector

Dry Cell Indicator

t:.

Ground ■=■

Fig. 78. — Diagram of Detector and Cell Circuit.

system in which the aerial wire connects with one end
of an inductance coil, while the opposite end of the lat-
ter leads to earth. This comprises that part of the
resonator equivalent to the open circuit, the closed
circuit being formed by connecting the inductance-coil,

[IVIRINQ DIAGRAMS FOR RECEPTORS

125

the coherer or other detector, and the condenser in
series, as shown in the diagram. Since the open cir-
cuit and closed circuits are connected directly to each

,5.

Condenser

To Relay or
Telephone Receiver

Dry CeJJ

Switch

To Relay or
Telephone Receiver

T Ground

Fig. 79. — Compound Conductive Coupled Resonator System.

other, it is termed a direct or conductive-coupled system.
This is the form of oscillating circuits used in the receptors
in the Telefunken system. In the actual receptor means
are provided for varying the value of inductance as is

126 WIRING DIAGRAMS FOR RECEPTORS

the case of the spark-gap, and the capacity is also made
adjustable, or should be.
Diagram of an Inductive-coupled Resonator. — In a

compound-circuit resonator where an inductive coupling is
used it is understood to mean that the aerial wire con-
nects with an inductance coil and the latter with a grounded
terminal as in the former instance, but this inductance
not only serves to tune the circuit, but also as the primary
coil of a small transformer, the latter sometimes being
called a jigger. The secondary of the transformer
makes up a closed circuit with the coherer through
one or two small condensers, as shown in Fig. 80. In
practice the condensers and the coils are arranged so
that their values may be changed and the periods of
oscillation in the open and closed circuits may be
tuned to each other and so be productive of the best
results.

Wiring Diagram of Relay Connections. — Of the instru-
ments used in a printing receptor the relay only has
double contacts. Relays of whatever type, ordinary or
polarized, are provided with four binding-posts, the coils
of the magnet being connected to the first two, while
the armature lever carrying on its end a platinum point
and the stationary platinum point with which it makes
contact are connected to the other two posts, as shown
in Fig. 81. The coherer and the dry cell are connected
in series with the relay magnets and the Morse register,
tapper, and battery in parallel with the contact
points.

HAIRING DIAGRAMS FOR RECEPTORS.

127

Wiring Diagram of Aerial Wire System, Coherer, and
Relay Circuits. — ^The coherer and relay circuits of

Condenser

o
o

To Relay

Dry Cell

To Relay

F Ground

Fig. 80. — Compound Inductive Coupled Resonator Circuit*

a receptor of a Telefunken set is shown in Fig. 82, and
while the receptors of this type in other systems may
not be connected exactly as in this one, there is very little
difference and the accompanying diagram will suffice

128

IVJRING DIAGRAMS FOR RECEPTORS

•«3

P
P

a>
o

r»

Morse Regis'^er

Tapper

H
o

>
5

IVIRING DIAGRAMS FOR RECEPTORS

129

«tf

■r

Condenser

Swrtch

==■ Grdu^ll

o
a;

To Relay

Dry Cell

To Relay ^

)•■ J

Fig. 82. — Compound Close Coupled Resonator System.

< f

I ■-'

I30 HAIRING DIAGRAMS FOR RECEPTORS

to enable the operator to connect up any receptor using
a coherer and relay. The tuning coil is provided with
three adjustable plugs all of which are connected with
flexible conductors; the upper plug leads to the aerial
through a variable non-inductive resistance, the purpose
of which is to cut down the energy of the received
electric waves when the distance between the transmit
ting station and the receiving station is comparatively
short; a second and shorter aerial wire may be used
instead of the long-distance aerial with the resistance
thrown in if preferred, and some of the Atlantic liners
are thus equipped. The two lower plugs, also fitted
with flexible conductors as mentioned above, are con-
nected to the lower end of the tuning-coil, which in
turn leads to earth.

The ends of the tuning coil are connected in series with
the coherer, dry cell, coils of the relay, and a small variable
resistance, this arrangement forming the closed circuit.
Bridged across this closed circuit is a small spark-gap, so
that in case an electrical storm should occur, or when the
atmospheric conditions are such that the aerial system
becomes unduly charged by electricity, these charges
instead of passing to the earth through the coherer, which
would render it unfit for further use by destroying its
sensitiveness, will pass through the alternative path
offered by the spark-gap, since static charges suddenly
released will break down a thin film of air rather than
force its way through the filings of a coherer. It may
again be asked why it does not dissipate its energy into

IVIRING DIAGRAMS FOR RECEPTORS

131

the earth through the inductance coil, but it must be
remembered that inductance has a very great retarding
influence on an electric current.

Also bridged across the closed circuit and in parallel
with the spark-gap is a pair of small condensers that
may or may not be adjustable, but should be in order
to obtain the best results. These small condensers not
only tend to check the discharge of atmospheric elec-
tricity through the coherer, but they also serve to pre-
vent the current from the dry cell from leaking through
the earth connections and tuning coil.

x:
o

O
o

-Stop

-Armature Contact

"Stationary Contact

«/»
»

Battery

Fig. 83. — Wiring Diagram of Internal or Local Circuits.

Wiring Diagram of Internal Circuits. — The internal
circuits, that is those that are closed through the medium
of the relay, include the tapper, polarization cells, Morse
register and a call bell. These are connected up in parallel,
as indicated i^ fte 4iagram Fig. 83, and are consequently

132 fVIRING DIAGRAMS FOR RECEPTORS

operated from the same battery of dry cells. The polarized
cells are connected in series, and these are placed across
the contact-points of the relay; they absorb the excess
energy produced by the condenser action of the circuit,
which would otherwise cause an excessive spark to
pass between the relay contacts and set up oscillations
of small magnitude but amply great enough to affect
the filings of the coherer, just as would a received
impulse.

The magnets of the decoherer or tapper, the Morse
register, and the call-bell are wound to the same resistance,
since these are energized by the same battery. A switch
is provided so that the bell can be cut out after ringing
up the operator.

Wiring Diagram of a Complete Receptor. — This is
shown in Fig. 84, and is a combination of Figs. 82 and 83
coupled together, when they present a much more com-
plex aspect than do the different circuits shown separately.
All the apparatus above described except the tuning
coil is mounted on the receptor stand, as is also a switch,
especially designed for the purpose, for breaking the
connection of the aerial in receiving and which simultane-
ously closes the primary circuit of the sending apparatus.

Wiring Diagram of a Receptor with Magnetic Detector.
— In the Marconi system now in commercial use in this
country a magnetic detector is employed, and the fol-
lowing connections shown in Fig. 85 are used. A tun-
ing coil is connected to the aerial wire by a flexible
conductor terminating in a plug. A second flexible wire

IVIRING DIAGRAMS FOR RECEPTORS

^ZZ

C
ci5

3
U

a>
o

I— SpB^UOQ

|BuaV

"DUl

■M

UU i.

9DUB;sisa^

jgSUQpUOQ

o
O

.<2 SJOpnpuoQ aiqi^dij

J8UIUJSU1BJJ_

}0 Ajbuiuj 0J_^

t-i

L|o;iMS |iBuav

IVIRIhIG DIAGRAMS FOR RECEPTORS

with a plug end makes contact with one of the middle
turns of wire and leads to the earth direct. A third

? 5*

"^ s

< Q

n
o

•-1

Aerial

Flexible

Flexible Conductor

flexible wire with a plug end makes connection with a
lower turn of the inductance coil; this last named con-
ductor leads to a small adjustable condenser, which in
turn connects to one end of the primary of a small trans-
former coil, while its other end is joined to a second earth-

fVIRING DlApR/iMS FOR RECEPTORS

135

terminal; shunted around this primary coil is a second
adjustable condenser. Around the primary of the trans-
former coil is wound a secondary coil of finer wire, the
terminals of which connect to the binding-posts of a
telephone receiver.

Wiring Diagrams of Receptors with Electrolytic and
Crystal Detectors. — Electrolytic and crystal detectors

Condenser

■M
3

C
3
O

Fig. 86. — Wiring Diagram for Crystal Detector Receptor.

are largely used in commercial systems and by the Army
and Navy departments. There are various methods for
hooking them up with the aerial but the accompanying

IVIRJNG DIAGRAMS FOR RECEPTORS

diagrams are typical and are probably the best available
at the present time. In Fig. 86, the aerial is connected
to a double-slide tuning coil through the shding con-
tact Ay and the ground is coupled in on the opposite side
through the slide B. The tuning coil leads to a small

Telephone

^ ' 0)

Potentiometer

Dry Gel!

Fig. 87. — ^Wiring Diagram for Crystal or Electrolytic Detector.

condenser of fixed value, which with either an electrolytic
or a crystal detector is connected in series with the lower
end of the coil through the sUde jB; the telephone receiver
is merely shunted around the detector.

Where it is desirable to use a small direct current in
connection with a detector the connection may be made as

IVIRING DIAGRAMS FOR RECEPTORS

137

shown in Fig. 87. For this purpose a triple-slide tuning
coil is advisable. The aerial is connected to the tuning
coil through the slide A and the ground is joined directly
to the lower end of the coil. The condenser, the detector
and the potentiometer are connected in series with the
tuning coil through the slides B and C The telephone

Fig. 88. — Wiring Diagram for Auto-detector Receptor with Oscillation

Transformer.

receiver is shunted around the condenser and a dry-cell
is shunted around the resistance of the potentiometer.
Fig. 87 is a wiring diagram of an auto-receptor in which
a tuning oscillation transformer is used. The aerial
connects wiA the upper terminal of the primary coil of
the transformer. The coil is grounded through a sliding
contact Ay a variable condenser being connected in the
ground wire. A fixed condenser and the detector are

138 HAIRING DIAGRAMS FOR RECEPTORS

connected in series with the secondary of the transformer
through the upper terminal of the coil and the sliding con-
tact B. The telephone receiver and potentiameter are
shunted around the detector and finally a dry cell is
shunted around the resistance of the potentiometer.

The detector circuits of Figs. 86 and 87 may be con-
nected with the oscillation transformer of Fig. 88, or
the aerial wire circuits of Figs. 86 and 87 may be used
in combination with the detector circuit shown in Fig.
88. By changing the circuits around a variety of hook-ups
may be had to suit individual requirements.

CHAPTER VIII
THE APPARATUS IN ACTION

Preliminary Remarks. — Having explained the element-
ary theory upon which the transmission and reception of
electric waves are based, and having described the various
apparatus used for setting up and indicating these waves,
it will be well, before the methods of adjusting the instru-
ments are discussed, to follow out in detail the processes
involved when the apparatus is in action; to do this w^e
must begin by following the low-voltage current as it is deliv-
ered by the generator through the induction coil, or trans-
former, at the sending station, and then ascertain how the
energy of the impressed oscillations is supplemented by a
small direct current from a dry cell at the receiving station.

Action of an Induction Coil. — The principal functions in
the conversion of a low-voltage current into a high-tension
charge — such as we have immediately prior to the transfor-
mation of the static charge into kinetic energy, i.e., electric
oscillations, by the electric spark, or disruptive discharge —
take place through the medium of the induction coil and
hence is due to mutual induction. The making and break-
ing of the primary circuit by the inter ruptor, and the re-

139

140 THE APPARATUS IN ACTION

duction of the spark between the contact-points of the
latter by means of the condenser, are details that are not
only interesting in their theoretical aspects, but of vital
importance in the successful working of the transmitter.
Before considering the action of these devices a brief sum-
mary of the principles of mutual induction willservx to
make the operation of an induction coil comprehensible
and the more complex phenomena of the interruptor and
condenser understandable.

(a) When the key is made to close the primary circuit
see Fig. 89, and the direct current is permittjed to flow

Closed Magnetic
Line of Force

Primary Electric Current Secondary Electric Current

Fig. 89. — Transformation of Electric Current into Magnetic Line of

Force, and the Latter Back into an Electric Current.

through the inductor or primary of the induction coil, a
large per cent of the electric energy is transformed into
magnetic energy in the form of closed or eUiptical lines of
force that expand like those produced on the surface of a
pond when a stone is dropped into it. If a core of soft
iron is placed inside the primary coil, these magnetic lines
of force may be concentrated, for iron possesses a greater
permeability than air and the non-magnetic metals. Fig.

THE /IPP/iRATUS IN ACTION

141

90 shows how the magnetic lines of force which are formed
at right angles to the diameter of the turns of wire are
carried through the iron core and form closed loops through
the air surrounding it.

(b) Let us ascertain now what the action will be when
there is another or second coil of wire slipped on and over

f IG.QO.- Diagram showing^ How Magnetic Lines of Force are Set Up in
the Core of a Coij^ and How the IxK)ps Intersect the Secondary Coil.

the first or pimary coil. Assuming that the circuit is
closed through the key, and that the electric current is
converted into the magnetic lines of force as explained, the
latter in passing from one pole of the core to the other w ill
intersect or thread through the secondary coil; when this
condition of affairs takes place the magnetic energy will
be transformed back into an electric current in the outer

142 THE APPARATUS IN ACTION

coil. The current thus set up, however, is of but moment-
ary duration and takes place only on closing the primary
circuit or on breaking it, the current flowing first in one
direction and then in the other, for there must be either a
rise or a fall in the intensity of the magnetizing force in
order to produce an electric current in the turns of wire
intersecting it. The purpose then of the mterruptor
is to make and break the circuit as rapidly and as sharply
as possible.

(c) If an induction coil was woimd with a primary and
a secondary coil of the same number of turns of wire, the
potential or voltage impressed on the former would be
developed at the terminals of the latter, if we regard the
losses due to the transformation as negligible. In this
case the ratio of transformation, as it is termed, would be
unity, for the law of transformation states that the ratio
is directly proportional to the number of turns of wire on
the primary and the secondary coils, while the amount of
energy delivered at the terminals of the secondary is prac-
tically equal to that which flows through the primary;
consequently the potential of the secondary may be ex-
ceedingly great when compared with that of the primary,
the amount of current being, of course, relatively less.

{d) The condenser shunted around ,an interruptor
is inactive when the make-and -break points of the latter
are in contact and the full value of the current is flowing
through the primary circuit, but the instant the contact-
points begin to separate or break, the increased resistance
causes the primary current to begin to charge the con-

THE APPARATUS IN ACTION. I43

denser, and this continues until the charge is maximum
or the fixed and movable points of the interruptor
again make contact. An interruptor where the
break takes place suddenly, requires a condenser of
much smaller capacity than where the break consumes a
longer time; this must not be taken to mean the period of
interruption, that is, the length of time to complete the
cycle between a make and a break, but the time measured
from the instant the break begins to take place until the
current ceases to flow between the contact-points.

The reason a smaller condenser can be used where the
break is sudden is that there is less time for the potential
of the primary to rise to a point where it can produce an
excessive spark. Without the condenser it is impossible
to break the circuit very quickly, for, though the mechanical
portion of the interruptor works at the same speed, the
large spark produced between the contact points heats the
air between them, rendering it a good conductor, and the
current continuing to flow prevents the potential from
falling from its highest value to its lowest value in the
shortest possible time. On the other hand the condenser
should have the smallest capacity that will effectually
reduce the sparking at the interruptor contacts. When
these conditions are properly fulfilled the secondary coil
will develop a potential difference at its terminals that will
give the longest spark possible with the coil used.

Action of a Transformer. — Where a transformer is
used instead of an induction coil there is no need of an
interruptor, and in order to obtain the maximum and

144 THE APPARATUS IN ACTION

minimum values of electromotive force necessary to ener-
igze the secondary coil a generator producing an alter-
nating current must be resorted to; this arrangement is
shown in Fig. 72, Chapter VI. Here the same laws of
mutual induction are in evidence as in the case of the
induction coil. Where transformers are employed the
potential at the terminals of the secondary coil seldom
exceeds 50,000 volts, and more often only 25,000 volts are
developed. That a greater amount of energy may be
utilized in the production of the oscillating currents, the
terminals of the secondary are connected with the inside
and outside coatings of a battery of Leyden jars; Avhen
the latter are charged to their maximum capacity they
discharge across the spark-gap of the oscillation system.

The Action of a Simple Sending System. — In one
of the earlier chapters the first principles of the disruptive
discharge, electric oscillations and electric waves were
discussed and their elementary theoretical functions were
stated. A simple oscillation circuit together with the
high-tension secondary circuit and low-voltage primary
circuit is shown in Fig. 91; it will be observed that these
are drawn as separate parts, for, while they are physically
connected at all times and electrically connected part of
the time, there are certain periods when their functions
are quite as distinct as though ttie circuits were entirely
removed from each other.

For instance, after the secondary is energized by the
action of the current flowing in the primary, it charges the
opposite arms of the oscillation circuit formed by the

THE APPARATUS IN ACTION

145

I Key

Spark-Gap

o a

Secondary Coil

Primary Coil
Condenser

To Dynamo

— ^

n«^

n^n^

Lnterruptor
Fig. 91. — Diagram of Action of a Simple Sending System.

146 THE APPARATUS IN ACTION

aerial wire on the one side and the grounded terminal on the
other. The high -potential energy alternately changes its
direction, as we now know, each time the primary circuit
is made and broken, hence its frequency of alternation
is comparatively low. When this low-frequency but high-
potential current flows into the oscillation system its
energy is no longer kinetic but static, and it is therefore at
rest, like a gas under pressure, until it becomes sufficiently
great to puncture the insulating partition of air in the
spark-gap.

When this action takes place the static now becomes
kinetic energy, and an exceedingly high frequency of
alternation is produced in the circuit, when it is termed
an oscillating current. As this high-frequency and high-
potential current oscillates through the aerial- wire system
its energy is changed into an altogether different form, very
much as in the case of low-voltage current electricity
changing into magnetic lines of force, in that it sets up a
disturbance in the ether and at right angles to the wire
conducting the oscillations, but instead of closed lines of
force the propagation assumes the form of undulations
termed electric waves.

Action of a Conductive-coupled Sending System. —
Where an open and a closed circuit are coupled together,
as shown in Fig. 92, the spark is produced in the closed
circuit, and the high -potential and high-frequency cur-
rents surging through the system thus formed is im-
parted to the open-circuit system, which radiates the
energy as electric waves. It will be observed by referring

THE APPARATUS IN ACTjON

147

0).

Condenser

6
O

Q.
(0

LU
O

*=* Ground

Fig. 92. — Diagram of Action of a Conductive-coupled Sending

System,

148 THE APPARATUS IN ACTION

to the diagram that a second closed circuit is formed by
the spark-gap in series with the secondary of the induction
coil, but it should be understood that the oscillations
cannot surge through this closed circuit, for the inductance
of the secondary is so excessive for the enormously high
frequency oscillations that it acts as a choke-coil, with the
result that the greater portion of the energy is confined
to the open and closed oscillation circuits. Before the
oscillations can be communicated to the aerial and
grounded wires their energy must surge through the
Leyden-jar battery and the inductance coil. As these
are, respectively, adjustable and variable, the closed cir-
cuit can be, and indeed it must be, tuned to the period
of oscillation best adapted to the aerial-wire system.
When tuning is effected the oscillations of the closed cir-
cuit will flow through the open circuit in the same period
of time, and there will be no opposition currents to waste
the energy, but instead the maximum amount will be
available for radiation from the aerial.

Action of an Inductive-coupled Sending System. — In
loose-coupled systems where a high-frequency and
high-potential transformer is used to further increase the
potential of the oscillations impressed on the open circuit
by the closed circuit, the action is a little different from
that just described. The secondary of the induction coil
of course performs the same functions as before, charg-
ing the Leyden-jar battery until the energy becomes great
enough to produce the spark. The high-frequency cur-
rent surges in the closed system as above stated, but the

THE APPARATUS IN ACTION

149

energy, instead of being directly impressed upon the open
or radiating circuit, is transformed into oscillations of
higher potential, while its frequency remains constant,
the action being very similar to that produced by an

B
o

Leydien Jars

Q.
cd

Le yden Ja rs

Fig. 93. — Diagram of Action of an Inductive-coupled Sending System.

interrupted or alternating current in its conversion by an
induction coil; in other words, the primary coil links
the turns of the secondary coil with a rapidly oscillating
magnetic flux, which produces in the secondary coil of
the transformer, due to its greater number of turns of

150 THE APPARATUS IN ACTION

Wire, oscillations of higher potential, and the energy of
these is damped out by the aerial wire in the usual
way. Fig. 93 indicates the direction of the current during
one-half a cycle.

i Action of a Receiving System. — When the electric
waves that are radiated by the aerial wire of a distant
station impinge upon the aerial wire of the receiving
station, the energy of which they are built up is converted
into electric oscillations, very much in the manner that
magnetic lines of force are changed into electric currents
when they intersect a wire conductor. These oscillating
currents in the resonator or receiving aerial have exactly
the same frequency as the oscillations in the radiating
aerial that emitted them, provided, of course, that the
oscillator and resonator have the same relative values of
inductance, capacity and resistance For a diagram of a
simple open-circuit resonator see Fig. 2, Chapter I.

Action of a Conductive-coupled Receiving System.
— Where the receiving system comprises an open and a
closed circuit, as shown in Fig. 94, the electric oscillations
set up in the open circuit are impressed directly on the
closed circuit, the action being diametrically opposite to
that which takes place in the transmitting oscillation
system; the advantage of coupling the two circuits to-
gether is that in the open circuit, as we have learned, the
electric oscillations are damped out in two or three swings;
but where these are impressed on the closed circuit they are
damped out very slowly and produce a cumulative effect
on the coherer or other detector.

THE APPARATUS IN ACTION

151

Action of an Inductive-coupled Receiving System. —

Where an oscillation transformer is used to inductively

3
O

O
o

Dry Cell

Telephone Receiver

■«-'
O

Fig. 94. — Action of a Conductive-coupled Receiving System.

couple the open circuit with the closed circuit, as shown
\A Fig. 95, the oscillations are transformed by mutual

152

THE APPARATUS IN ACTION

in(Juction from the open to the closed circuit, and there
they surge with even greater persistency than in a con-

O
E

CLt

LU
O

Dry Cell

Telephone

Fig. 95. — Action of Inductive-coupled Receiving System.

ductive-coupled system; but there is a greater loss of
energy in transformation, so that one scheme is about
as effective as the other.

THE APPARATUS IN ACTION 153

Action of a Coherer. — When an oscillating current of
either a plain or compound-circuit receiving system surges
through the coherer, as previously described in this work,
the filings are drawn together as though they were magnet-
ized, and, following this, the minute sharp edges are
welded, forming a practically continuous conductor until
the coherer is tapped back. To perform this action of
reducing the resistance of the coherer filings is the sole
function of the oscillating current in the receiving aerial.
The coherer simply acts as a delicate relay, for it permits
the utilization of a current of much greater strength than
the oscillating current has, and, being a direct current,
it is adapted, where the other is not, to operate a polarized
relay, when all the current needed can be supplied.

Action of the Polarized Relay. — ^When a current from
a dry cell is allowed to flow through the coherer by the
action of the oscillating current, the former passes through
the coils of the relay magnet. Since both poles of the
electromagnet are of the same polarity when there is no
current flowing, the armature carrying the movable con-
tact-point will remain stationary; but when the current
flows through the coherer one of the poles of the electro-
magnet changes to the opposite sign, and the armature
is attracted by the one and repelled by the other, throwing
it into contact with the stationary point and so closmg a
second internal circuit.

Action of the Tapper. — ^In the circuit which is closed
by the relay contact-points are the dry battery, tapper, and
Morse register. When the relay closes the second circuit

154 THE APPARATUS IN ACTION

a portion of the current from the battery of dry cells flov. s
through the coils of the tapper magnet, causing the arma-
ture carrying the hammer to be attracted to its poles when
it strikes the coherer; the blow breaking the filings apart,
the coherer and relay circuit is broken, which in turn
breaks the circuit in which the tapper is placed. As the
tapper has a vibrating armature like an electric bell, it
may strike the coherer half a dozen times before the cir-
cuit is finally broken.

Action of a Morse Register. — The Morse register,
being placed in a circuit parallel with the tapper, of
course receives its pro rata of the current, and simultane-
ously the current, flowing through its magnet, releases a
spring motor that carries the tape forward, and at the
same time a lever fixed to the armature, through w^hich
the band of paper slides, carries the latter upward into
contact with an inked disk, which prints the message in
dots and dashes. The time constant of the vibrating
armature of the tapper must be low compared with
that of the armature lever; that is, the first must be able
to strike three or four strokes while the latter moves up
and down once, or else the dots will not properly run
together to form a dash w^hen a succession of oscillating
currents representing a dash is received.

Action of an Electrolytic Detector. — Detectors of this
type, Fig. 52, may be connected directly to the aerial and
grounded wires or in coupled systems, as in the case of the
coherer. When the current from the dry cell flows through
the detector minute bubbles of gas, due to polarization, are

THE APPARATUS IN ACTION I5S

formed on the point of the fine platinum wire when the
current is practically cut off; now when an electric

oscillation surges through the detector it breaks through
the insulating film of gas and permits a momentary cur-
rent from the dry cell to flow through the telephone
receiver when the sound of the sending spark is heard.

Action of a Magnetic Detector. — In this detector the
moving band of soft-iron wire, Fig. 85, is constantly
magnetized by two small horseshoe nagnets; the primary
coil through which the band travels is connected to the
aerial and grounded wires, and the terminals of the second-
ary wire to the telephone receiver. Now when there are
no oscillatory currents surging through the resonator the
magnetic intensity remains unchanged, and no sound is
heard in the telephone receiver; but when the oscillations
take place these vary the magnetism of the wire band
when alternating currents are induced in the secondary
coil, and, flowing through the telephone receiver, are
rendered audible.

Action of a Crystal Detector. — When electric oscilla-
tions pass through a crystal detector. Fig. 50, they are
rectified or changed into direct currents and for this
reason it is not necessary to use a battery current to
make it operative. With certaui crystals, however, a
battery current seems to increase their sensitiveness.

The crystal detector is current operated; that is, its
action depends on the total energy absorbed by it and
it can therefore be used for long trains of waves of small
amplitude — a valuable feature where sharp tuning is

156 THE APPARATUS IN ACTION

necessary. Diflferent from voltage-operated detectors,
as the coherer, the change in the ohmic resistance of a
crystal detector is very small, so that only the telephone
receiver has proven a satisfactory indicator when used
with it.

Another important feature is that there is evidently
no change in the sensitiveness of these detectors when
operated with different frequencies of oscillations so that
the detector gives just as good results with one type of
transmitter as with another.

CHAPTER IX

ADJUSTING AND OPERATING THE INSTRUMENTS

Notes on Adjusting. — The adjustments required for the
proper working of the sending and receiving instruments
comprise (a) those of the low-voltage circuits of the
induction coil, (b) those of the high-potential circuits of
the oscillator, (c) those of the low-voltage circuits of the
receptor, and (d) those of the high-frequency circuits of
the resonator. The simplicity or complexity of the adjust-
ments depends largely on the nature of the system
employed. Where simple open-circuit oscillators and
resonators are used there are no adjustments to be made,
if we except that of the spark-gap, as the values of induct-
ance, capacity, and resistance are fixed; the older forms
or systems of wireless telegraphy utilized these definitely
fixed radiator and receptor circuits, but the more recent
modifications are provided with compound circuits, and
these require adjustment in order to obtain the most
favorable results. In the older makes of apparatus the
coherer, tapper, and Morse register were used for receiving
the messages, but this complicated apparatus has been
largely superseded by the more simple and rapid auto-

157

1^% ADJUSTING AND OPERATING THE INSTRUMENTS

detector and telephone receiver, the number of adjust-
ments having in consequence been greatly reduced. The
low voltage or internal circuits of the transmitter remain
practically the same as in the beginning of the art, but
here the adjustments are few and easy to make.

Adjustment of Instruments in the Primary Circuit. —
The adjustments of the transmitting apparatus, where
the aerial wire and earthed terminal are connected direct
to the spark-gap, are confined to the primary circuit. A
rheostat is connected in the primary circuit, and enough
resistance should be thrown in to prevent excessive spark-
ing at the contacts of the interruptor, or, where a mercury-
turbine or electrolytic interruptor is used, the amount of
current needed can be roughly estimated by the sparking
at the contacts of the key. A volt meter shunted across
the circuit, and an ammeter in series with it, are useful
instruments to measure the initial energy used, but they
are not always to be found in the different stations

(a) When the amount of current flowing through the
primary circuit seems to be about right the interruptor
is adjusted; if it is of the vibrating spring type, tlie ad-
justing screw should be turned so that it will start easily
and quickly when the key is depressed, closing the circuit,
and a partial turn one way or the other will often reduce
the sparking between the platinum contact-points to a
minimum without appreciably affecting its starting action.

{b) Where a mercury turbine interruptor is used the
adjustments are limited to increasing its speed of rotation
and varying the length of its segment. Where a potential

ADJUSTING /IND OPERATING THE INSTRUMENTS 159

of 1 10 volts is the initial pressure the shortest segment
furnished with the device, which is a quarter of a circle
in length, should be used; if the current is taken at 60 or
65 volts, then the longest segment, which has a length of
half a circle, is best adapted. The speed of the turbine
is important, and as this depends on the motor, see Fig.
70, the latter is regulated by a small rheostat. The
speed of the turbine should be run up until a white spark
is produced, when it will emit a continuous sound, and
the ear soon becomes trained to know that this is the
proper kind for good working. The current can now be
further increased until the ammeter shows that 8 to 10
amperes arc flowing through the primary of the coil.

{c) An electrolytic interruptor requires practically only
one adjustment, and that is to raise or lower the platinum
anode, though the electromotive force may be varied
with excellent results; a potential of at least 40 volts is
required to operate it properly. Nearly all electrolytic
interruptors are provided with a cooling-worm, and the
operator should see that there is a stream of water flowing
through it; otherwise the electrolyte will become heated,
and this diminishes the rate of interruption, and, if per-
mitted to continue, will cause it to stop altogether.

{d) The contacts of the Morse key soon become
roughened by the heating action of the sparks on breaking
contact, and must be looked after; when their opposed
surfaces become uneven they should be put into condition
with a file. This also applies to the platinum contacts of
the vibrating spring interruptor.

i6o ADJUSTING AND OPERATING THE INSTRUMENTS

(e) Where an adjustable condenser is shunted around
the break of the interruptor a much more satisfactory
spark can be obtained across the discharge-gap than with
a condenser having a fixed value; a lever is so arranged
that any value may be had from zero up to its full capac-
ity, though of course this is obtained by steps.

Adjusting the Spark-gap. — Since, in a simple open-
circuit oscillator, the aerial wire and the earthed terminal
are fixed to opposite sides of the spark-gap, there is
nothing to adjust but the length of the spark. The spark-
gap should be cut down when sending messages to about
]yV to ^ of the longest sparks the coil is capable of giving;
if too long a spark-gap is used, the resistance offered to
the released charge is so great that the current may not
oscillate, but will simply pass through the system in one
direction. But when the spark-length has been cut down
the operator must see that the necessary amount of resist-
ance is in the primary circuit; for, should it be worked with
an overload, the coil may be injured, due to static strains
set up within it.

To Time a Coupled Transmitter. — The following
method of tuning applies to the tuning of either close-
or loose-coupled oscillation circuits. The primary cir-
cuits are adjusted as described in the preceding para-
graphs, and it now becomes necessary to tune the closed
circuit to the open circuit. The hot-wire ammeter is
provided with several shunts, and the shortest of these
should be placed in the instrument, in accordance with
the instructions accompanying it; it is then ready to be

j4DJUSTING and operating the instruments i6i

(.onnected in circuit with the aerial wire, as shown in Fig.
96. The contact-plugs or spring-clips should be placed
together on the middle turns of the inductance coil and
their positions varied, not relatively, but they should be

Induction Coil

To Dynamo

-=• Grpund
Fig. 96 — Hot-wire Ammeter in Aerial.

moved together until a point is found where the reading
of the ammeter is the highest; to ascertain this the primary
circuit must be closed by the key for a sufficient length
of time to permit the needle of the ammeter to come to
rest.

1 62 ADJUSTING AND OPERATING THE INSTRUMENTS

Having gotten the best results in this manner, a longer
shunt may now be inserted in the ammeter and the upper
contact-plug or clip moved gradually away from the lower
contact, when a position will soon be reached where the
reading of the ammeter will give a still higher value,
showing that now the open-circuit aerial-wire system and
the closed oscillation-circuit are more or less accurately
tuned to the same periods. If the interruptor is of the
mercury-turbine or electrolytic type, it may be further
adjusted and a greater amount of energy can be used;
then the upper plug or clip may again be adjusted until
the reading is maximum, when the circuits may be said
to be fairly well tuned. As the hot-wire ammeter is not
a very accurate instrument, several readings should be
taken to determine the value of the current energy of
the oscillations surging in the aerial wire, and the mean
reading taken as standard.

To Tune the Aerial-wire System to Emit a Given Wave-
length. — The best results are obtained in wireless teleg-
raphy when the transmitter and receptor are tuned to the
same wave-length; when they are thus tuned so that they
will be CO- resonant they are said to be syntonized. Where
only two stations are engaged in communication the
receiver can be tuned to the same period of oscillation as
the sender, as will be described presently; but when a
receptor is to receive messages from two or more trans-
mitters, it then becomes necessary to tune each of the
latter to emit waves of a length suitable for the receptor.

It has been previously stated that a plain aerial wire

ADJUSTING AND OPERATING THE INSTRUMENTS 163

system, that is, one in which there is neither inductance
coil nor condenser inserted, will emit a wave approxi-
mately four times its length, and therefore where two 01
more sending stations are to be used in connection with
one or more receiving stations the aerial wires of the
former should be practically the same length. While it is
comparatively easy at shore stations to have the aerial
wire of the same length, on board ship the conditions met
with are very different; yet, as, for instance, in the Navy
and the mercantile marine service, it is essential that all
stations, both on ship and shore, should use the same
wave-length.

(a) This is accomplished in the following manner:
First, a wave-length should be selected that is equal to
or a httle longer than that. emitted by the longest of the
aerial wires used. A tuning-device, of which one form is
shown diagramatically in Fig 97, is called intd action.
This device comprises an adjustable spark-gap formed
of needle-points, a condenser of small" capacity, and a
portable tuning-coil of the same relative proportions
as the tuning-coil used in the receiver, namely, each
turn of wire represents a length of one meter. The
length of each turn of wire is really only 90 centimeters?
but by adding the increased value given by the inductance
each turn will increase the length of the wave emitted
by the aerial 4 meters; as each tuning-coil has 100
turns of wire, any wave-length from that produced
by the plain aerial wire up to 400 meters, when all the
inductance is thrown in, may be had at will.

1 64 ADJUSTING AND OPERATING THE INSTRUMENTS

In the Navy the ships are equipped with aerials having
a length, where possible, of 50 meters, and the wave is
of course about four times this length, or 200 meters;
the inductance and capacity of this open circuit are equal
approximately to those of a closed circuit containing seven
I -gallon Leyden jars and one turn of inductance. To tune

Needle-Point Spark-Gap

'To Closed Circuit

Ground ""^

Fig. 97. — Tuning Device.

an aerial that is less than 50 meters in length so that it
will emit a wave of 200 meters, the tuning-device shown
diagrammatically in Fig. 98, is connected to the closed
circuit formed of the Leyden-jar battery, the spark-gap,
and the inductance coil, all of which are included in the
cross-sectional drawing in the same figure. The sliding
contacts i and 2 on the coil of the tuning-device are

ADJUSTING AND OPERATING THE INSTRUMENTS 165

1 66 ADJUSTmC /1ND OPERATING THE INSTRUMENTS

brought closely together, as shown in the dotted line, and
set at a point equal to about one-fourth of the wave-length
it is desired to use.

The plugs or clips 3 and 4 of the large sending induct-
ance coil are also brought together on the middle turn;
the terminals of the sending spark-gap, on top of the
Leyden-jar battery or wherever it may be placed, are now
brought very closely together but without making con-
tact, and the aerial wire disconnected. All the resistance
in the primary circuit should be thrown in and the induc-
tion coil set into operation; the transmitting key is pressed
into contact and the resistance gradually cut out until a
good spark is produced in the regular spark-gap. The
small needle-point spark-gap of the tuning-device is
opened to about 2 centimeters, and the plug- contacts 3
and 4 of the sending inductance coil are adjusted until a
spark is produced in the needle-point spark-gap; con-
tinue to increase the length of this spark-gap and to
change the position of the plugs on the sending inductance
until the longest spark obtainable between the needle-
points is produced. When the position of the plugs 3 and
4 on the sending inductance coil gives the greatest potential
between the terminals of the tuning inductance coil, shown
by the longest sparks between the needle-points, then the
closed circuit of the transmitter is adjusted to the required
wave-length.

(b) This done, it is now necessary to adjust the aerial
wire to the closed circuit; the tuning-coil device may now
be disconnected from the closed circuit and the aerial

ADJUSTING AND OPERATING THE INSTRUMENTS l^l

wire connected to the end of the sending inductance
coil, as shown in the wiring diagrams for close coupled
oscillators, see Fig. 73. The hot-wire ammeter is now
connected in series with the aerial wire, as described in
this chapter under the caption To Tune a Compound-
circuit Transmitter^ and shown in Fig 96. The ter-
minals of the spark-gap are drawn apart until a gap of
0.5 centimeter in length is formed, and, after switching
on the current, the resistance offered by the rheostat should
be cut out until a heavy discharge is produced. Closing
the primary circuit by means of the key, the plug 4 is
moved away from 3 toward the bottom of the inductance
coil, until the hot-wire ammeter shows the highest read-
ing. When this point is obtained the aerial wire will
then be in tune with the closed circuit, and the wave
emitted by the aerial wire will have the length previously
decided upon. The necessity of determining with pre-
cision the positions of the plugs or clips on the sending
inductance coil cannot be too strongly impressed upon the
operator, for on the nicety with which this is done de-
pend the harmonious relations between the open and
closed oscillation circuits, and once that these adjust-
ments have been made, the operator should never change
them unless a new wave-length has been chosen, when
the tuning process must be done all over again.

To Tune a Coherer Receptor. — As we have seen
above, the transmitter is syntonized to the receptor, in-
stead of the latter to the former; for this reason all that
is needed by way of adjustment is to tune the closed to

1 68 ADJUSTING AND OPERATING THE INSTRUMENTS

the open circuit of the resonator or receiving circuits.
In the tuning device there is a small condenser which has
a capacity about equal to that of an ordinary coherer,
although these vary to some extent. If now the sending
aerial is syntonized accurately to the receiving aerial -
wire system, then the latter will require little adjustment
other than to slide the contact-points i and 2 of the recep-
tor tuning-coil (Fig 27) to a point indicating the wave-
length selected on the graduated scale. As contact 2 is
immediately above i, the inductance value of the few turns
from I to 2 is the same, or should be, as that portion of
the earthed terminal of the sending circuit.

The varying capacities of different coherers render it
almost impossible to syntonize the transmitter and recep-
tor with absolute accuracy, and the best way to test out
their co-resonant qualities is by the empirical method of
experiment. This consists of having some sending station
using the requisite wave-length to assist in trying it out.
To make the test the sending station should be located
about a quarter of its normal signalling distance away
from the receiving-station, or, say, 30 miles at the shortest,
or 40 miles at the longest range. A certain test letter is
chosen, for instance, the letter S, represented by three
dots; the operator at the sending-station sends this letter
over and over with a few minutes intervening between
each transmission, so that the receiving operator will
have ample opportunity to adjust the tuning coil; after
the test letter has been sent several times the operator
at the transmitting station should cut down the initial

ADJUSTING AND OPERATING THE INSTRUMENTS 169

current until the intensity of the spark is only half of
that ordinarily used in transmission; by careful tuning
the operator at the receiving station will secure a nice
degree of resonance, and when the sending operator cuts
out the resistance in the primary chrcuit the messages will
come in loud and clear.

Adjustment of the Receiving Instruments. — ^The oscil-
lator and the resonator circuits of the sending and receiv-
ing stations having been properly tuned and syntonized,
the receiving instruments must be adjusted. If these
include a coherer, relay, tapper, and Morse register, con-
siderable care must be exercised to keep them all in
working order, but where an auto-detector, like that of
the electrolytic or magnetic type, is used, these are
greatly simplified.

ya) The Coherer, — ^This is adjusted before it leaves the
hands of the makers, but if the conductor-plugs are
bevelled, forming a V-shaped pocket for the filings, the
operator is enabled to increase or decrease its sensitive-
ness within certain limitations, these changes being made
by merely turning the coherer partially around on its
longitudinal axis.

(6) The Relay, — The principal adjustment of the
internal circuit containing the coherer, dry cell, and
relay is made by means of a large milled screw pro
jecting from the case of the relay. By turning this screw
the position of the armature between the poles of the
magnet is varied, and in this way a very sensitive adjust-
ment can be had and one in which the feeblest current

I70 ADJUSTING /IND OPERATING THE INSTRUMENTS

flowing through the coherer will affect. The relay should
be tested frequently, once a day at least, and this may
be done in one of two ways; namely, (i) by placing it in
series with a resistance of 20,000 to 40,000 ohms, or so,
with a single dry cell, when, if it is in good working order,
it should readily respond; and (2) by grasping the bind-
ing-posts of the relay magnet-coils and permitting the
current to flow through the body, when, if it is adjusted to
its maximum sensitiveness, it should likewise operate.
Its sensitiveness must, however, be just below that point
at which its armature vibrates or chatters when the cir-
cuit is broken.

(c) The Tapper. — This must be adjusted so that it
taps the coherer a sharp quick blow. Some tappers have
three adjusting-screws: (i) the screw moving the coherer
to and from the hammer; (2) the screw for moving the
poles of the magnet to and from the armature; and (3)
the screw carrying the stationary point that makes and
breaks the circuit formed between it and a spring attached
to the armature. The tapper will not need to be adjusted
often, and a little practical experience will make this
easy.

{d) The Morse Register. — The adjustments of the
register are the most numerous and complicated, in virtue
of the fact that it is actuated electrically and operated
mechanically. Like all other parts of the sending and
receiving apparatus, there are slight differences in the
design of registers, but the usual type is provided with
these. adjustments: (i) a screw on the upper end of the

ADJUSTING AND OPERATING THE INSTRUMENTS 171

lever to which the armature is attached; this is to limit
the distance to which the armature can be drawn away
from the poles of the magnet; (2) a screw at the opposite
end of the same lever to limit the approach of the arma-
ture to the poles of the magnet; this screw, when the
armature is attracted by the magnet, strikes a pin pro-
jecting outside the brass case, which in turn releases the
mechanism of the spring motor which feeds the tape;
(3) a screw for adjusting the tension of the spring that
controls the upward pull of the armature, and this also
regulates the pressure with which the paper tape is brought
to bear against the revolving inked disk; (4) a small
weight that slides on a rod for governing the speed of the
motor through an escapement, so that the normal speed
with which the paper travels may be varied; (5) a screw
for adjusting the pressure exerted on the paper fed by
a toothed wheel, through a smooth wheel above it; and
(6) a screw for adjusting the length of the paper that
shall run out after the electrical mechanism has ceased
to act.

Should the register fail in any of its operations, some
one of the following troubles may account for it: (i)
The current of the dry battery may be two weak to pull
down the armature, and this may be due to the latter
having too much play, hence the screw in the upper end
of the lever should be adjusted so that the armature has
a very limited movement. (2) If the armature strikes
after it is drawn down by the action of the magnet, then
the screw in the lower end of the armature lever requires

IT 2 ADJUSTING AND OPERATING THE INSTRUMENTS

adjusting, so that the latter just clears the surfaces of
the poles of the magnet. (3) Not only may the battery be
weak or the armature too far removed from the magnet,
but the spiral spring whose tension controls the free
movement of the armature may be too great and should
be slackened; these comprise the adjustments for the
electrical portion of the register. (4) If the escapement
and small weight that governs its movements will not
act, it is due probably to the sticking of the releasing
mechanism. The cover of the register case must be re-
moved and an examination of the former will no doubt
reveal the cause; it may be due to dust having accumu-
lated therein, or the adjusting-screw on the lower end of
the armature lever which strikes it may be in or out too
far. (5) If the armature, releasing mechanism, and motor
work all right, but the tape does not travel as it should,
then look to the spring controlling the pressure of the
feeding wheels : this should not be too weak nor yet again
too strong. (6) The screw for adjusting the margin of
the paper may be screwed in or out so far as to cause it
to stick. The author has seen beginners work over these
adjustments without success, only to find that a screw had
been turned to the right or left so far that it seemed to
him who made the attempt that no amount of adjusting
could get it back into its normal position. There is a
happy middle road in making adjustments, and the
operator must see that he keeps to it. Then, even if the
adjustments have been correctly made, there is the pos-
sibility that too much friction is being exerted on some

ADJUSTING AND OPERATING THE INSTRUMENTS IT 3

of the spindles, and when every other means has failed
the register must be taken apart, cleaned, oiled, and set
up anew.

Testing the Receptor. — Finally, the coherer, relay, tap-
per, and battery must be adjusted so that they will work
in unison, and if the preceding instructions are carried
out, a little patience and practice, both of which are
absolutely essential to the making of a capable operator,
will result in an efficiently acting apparatus. When each
of the instruments has been adjusted the coherer and relay
circuit should be closed and then the devices tested out
collectively. This may be done by holding the buzzer
or testing-box a foot or two away from the coherer and
pressing the button; if the relay is properly adjusted, the
waves sent out by the buzzer will act upon the coherer,
and the other appliances will respond. If the instru-
ments do not respond, the relay should be readjusted
until these do.

Adjustment of an Electrolytic Detector Receptor. —
Where an electrolytic detector and a telephone receiver
are employed as a receptor all the complicated adjust-
ments of the coherer and Morse register are wiped out.
A variable resistance is inserted in the internal circuit
containing the detector and receiver, and half of the
resistance should be thrown into the circuit; then the
fine platinum wire point which dips in the electrolyte is
adjusted by means of a fine screw, until the oscillations
set up in the aerial by the incoming waves produces the
loudest sound in the telephone receiver. Then by vary-

174 yiDJUSTING AND OPERATING THE INSTRUMENTS

ing the resistance in the circuit ' a point will soon be
reached where the intensity of the sounds are maximum,
when it is ready to receive.

Adjustment of a Magnetic Detector Receptor. — This
is by far the simplest receptor as far as adjustment
is concerned, and fortunate is the operator whose lot it is
to be in charge of a station where it is used. After the
magnets are placed and the speed of the flexible band of
iron wire is regulated it is in working order.

Adjustment of a Crystal Detector Receptor. — For a
detector of iron sulphide the bright crystaline variety only
is sensitive. In combination with a phosphor-bronze
point, iron sulphide may be worked under considerable
pressure and it makes therefore a convenient and practical
crystal. In adjusting an iron sulphide detector, it must be
borne in mind that all points in the crystal are not sensitive
and consequently the bronze point must be moved around
until a sensitive spot is found. Do not attempt to polish
the crystal as this tends to destroy its sensitiveness.

Where the detector consists of two crystals in contact,
such as chakopyrite and zincite, the loudness of the
signals can be increased by using a dry cell and potentiom-
eter in connection with the detector. In this case the
positive terminal of the dry cell is connected with the
chakopyrite and the current of the cell should be cut

■

down to about i\ volt. Where a crystal has long been in
use and subjected to large battery currents its working
qualities are likely to become impaired; to restore a crystal
to its normal sensitivity, clean it with carbon disulphide.

ADJUSTING /fND OPERATING THE INSTRUMENTS. I75

To adjust a crystal detector receptor, place the head
telephones in position and bring the opposing crystals
or crystal and metal points together with as slight a
pressure as possible. Now regulate the flow of current
from the dry cell with the potentiometer and finally bring
up the signals to their maximum intensity by means of
the tuning-coil.

Learning the Alphabetic Codes. — As in ordinary teleg-
raphy, wireless messages are sent and received in alpha-
betic code, that is, \n dots and dashes. There are three
dift'erent dot-and-dash codes used, namely, the Morse,
the Continental, and the Navy Signal. The tw^o latter
codes are used in preference to the Morse, since the latter
has spaces as well as dots and dashes to represent the
letters. To learn to send and receive in code the beginner
should procure a telegraph key and connect it in series
with a buzzer and one or two dry cells, as shown in Fig.
99. A high speed is not necessary in sending wireless
messages, but accuracy is of the greatest importance.
To insure a readable message care must be taken to
make the dots and dashes of even length, equally spaced,
and clear-cut; the key must be firmly pressed down, held
in contact the required length of time and then released.
A speed of twelve w^ords per minute is rapid enough for
a system using a coherer and a Morse register, and when
this can be accomplished without effort the manual part
of the beginner's work is done, and then he can readily
get up to a speed of sending thirty or thirty-five words
per minute, which is required in systems using auto-

176 ADJUSTING AND OPERATING THE INSTRUMENTS

detectors and telephone receivers. Practice is the great
teacher, and practice alone will insure the proper style
of sending.

^11

Dry Battery

Key

Buzzer

i« »i

Fig. 99. — ^Learner's Set.

Wireless Telegraph Codes. — The three different tele-
graphic codes are given in Figs. 100, loi and 102, but
it is best for the beginner to learn to send in one of these
first — preferably the Continental, because it is the most
widely used — before attempting the others.

CHAPTER X
DIFFERENT MAKES OF EQUIPMENT

Various Systems. — After the first practical system of
wireless telegraphy was put into operation in 1896 by
Marconi, inventors and scientists in almost every civilized
country became imbued with the spirit of the new work
and bended their efforts toward improving the apparatus
so that the distance of transmission could be extended,
that greater accuracy in working could be effected, that
the speed of reception could be increased, and finally
that a means for obtaining selectivity might be found.
These efforts led to many different designs of equipments,
though all used the same fundamental principles as the
one originally devised; hence the number of different
so-called systems.

The principal improvements that have been made
during the past decade are those relating to the use of
coupled open and closed oscillation circuits, and the em-
ployment of auto-detectors in combination with telephone
receivers instead of the more complicated coherer and
Morse register receptors. The systems that concern the

operator are those now in use in the United States,

177

178

DIFFERENT MAKES OF EQUIPMENT

and at present these are the Marconi and the Tele-
funken. In England there are two systems in extensive
use, namely, the Marconi and the Lodge-Muirhead ;
in France, the Branly-Popp, the Rochefort, and the

• ^m

^••«

•• •

■■••

•

• ■■•

■■■■•

••••

• •

■■•^s

^•■■i

"■"

i^«

• •

••—

' • ••

•••

"■

••■■

• ••■■

—

•■■••

•• ••

• •• •

• •••

• ••«•

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PERIOD

INTERROGATION

COMMA

EjCCLAMATION

— —

••••••

— —

^•••*

• ■■•MB

— —■ -•

COLON

SEMICOLON

■■••^

■~~

««••••

Fig. ioo. — Morse Alphabetic Code.

Tissot; in Russia, the PopofiF; in Spain, the Cervera-
Baveria; while each of the countries cited has a num-
ber of lesser known systems; the details of these are
not described, for the reason that the average operator
in this country would probably never have occasion

DIFFERENT MAKES OF EQUIPMENT

179

to work them, and even if he should, a knowledge of
the various arrangements herein described would enable
him to adjust and operate them without a great deal of
trouble. The origin and rise of the system he is using
makes not only interesting reading, but the operator

• Mi.*

■■^•*

•■■■■

•

■■■■•

• •

•■■••

•

ERROR

UNDERSTAND

■ ■1 —

■■•••

Fig. ioi. — Navy Wireless Telegraph Code.

should be generally informed concerning it, and a short
description embodying the main points of each will be
found under the following captions.

The Marconi System.— Wireless telegraphy is not as
old as some of the works giving an historical retrospect
of the art would tend to have us believe, neither did it
come as a spectacular surprise, as is sometimes stated.

i8o DIFFERENT MAKES OF EQUIPMENT

As a matter of fact it rests upon a knowledge that dates
back just twenty-four years from the present writing. Its
evolution came about in this manner: In 1888 Heinrich
Hertz, a professor in Bonn University, Germany, con-
cluded from a series of experiments he had made that the
electric oscillations set up in an open circuit by means
of a disruptive discharge radiated their energy through
space not as static induction or magnetic lines of force,
but as electric waves that travelled at the speed of light.
These classic experiments created a profound impression
in scientific circles, and were being repeated by professors
of physics in different European colleges for the bene£t
of interested students. It was thus that WiUiam Marconi
witnessed the production of Hertzian waves in the lecture-
room of the Bologna University, Italy, presumably some
time in 1894. The young man — he was then only twenty
years old — conceived the idea of employing the waves for
signalling w^ithout wires, and his first attempts in this
direction were made shortly thereafter, or in 1895. Hav-
ing been successful in these primal attempts, he went to
England in May, and in June, 1896, he applied for a
patent.

The first experiments the young inventor made after
arriving in London were for the authorities of the British
Post-office, when he telegraphed without the aid of wires
with the new devices between the General Post-office and
the Thames Embankment, a distance of 300 feet. Deimon-
strations on a larger scale were now in order, and these
were conducted for the benefit of the War Ofl&ce and the

DIFFERENT MAKES OF EQUIPMENT

i8i

(T
orq

P-

1 82 DIFFERENT MAKES OF EQUIPMENT

Admiralty, the place selected being over Salisbury Plain,
across a distance of about two miles. The aerial-wire
system was not used in these primitive tests, but the
waves were reflected by large parabolic mirrors. The
result of the tests were satisfactory, but it was not until
the following year that the mirrors were dispensed with
and the aerial wires and earthed terminals were sub-
stituted in their stead when messages were transmitted
between I^avernock and Flat Holm, a distance of about
three miles, with aeriel wires at the transmitting and
receiving ends approximating 150 feet in height. This
was the resl beginning of the wireless telegraph in its
commercial form. In the same year the distance was
increased to eight miles, when messages were transmitted
between Lavemock and Brean Down, the aeriels being
sustained in the air by means of kites.

It was during these latter trials that Dr. Adolph Slaby
cf Germany was present, an event that was to have an
important bearing on the wireless situation a few years
later, for on returning to Germany he immediately set
to work and evolved a 'new system,' as we shall see
presently. From the results achieved on this memorable
occasion the Marconi system could no longer be consid-
ered an experiment but a commercial fact. The inventor
next visited his native land, and at Spezia, Italy, where a
shore station was established and two Italian baitle-ships
had been placed at his disposal, he proved conclusively
that his system was effective over a distance of twelve
miles.

DIFFERENT MAKES OF EQUIPMENT 185

It was at this important period of development that
the Wireless Telegraph and Signal Company, Limited,
was formed in London and incorporated in July 1897,
with a capital of ;£i 00,000; later the capital was in-
creased to ;£3oo,ooo and the name changed to Mar-
coni's Wireless Telegraphy Company, Limited. The
new company erected two stations 14 miles apart, one
at Bournemouth and the other at Alum Bay, Isle of
Wight, and here a long series of tests were made during
all weathers and seasons of the year. It was while these
trials were in progress that the distance was increased to
18 miles, when messages were exchanged with an outgoing
steamer. Lloyd's Corporation, in May 1898, now be-
came interested in the new method of transmission and
had equipments installed at Ballycastle and Rathlin
Island in the north of Ireland. The system was next
used to report the Kingston Regatta for the Daily Express
of Dublin, and more than 700 messages were sent be-
tween the ship that carried the apparatus and the shore
station; then, a month later, the apparatus was used for
the benefit and behoof of royalty; it was installed in the
royal residence at Osborne and on the royal yacht Oshorney
where the Prince of Wales, the late King Edward, was on
board suffering from a serious accident, and here again
communication was successfully maintained.

To demonstrate the value of the new telegraphy more
thoroughly than it had yet been, the Marconi Company,
in December 1898, installed instruments at the South
Foreland Lighthouse and the East Goodwin Lightship,

1 86 DIFFERENT MAKES OF EQUIPMENT

which lay to some 12 miles away. Its usefulness was
conclusively proven when a steamer that had stranded on
the Goodwin Shoals was saved a loss of over ;i£5o,ooo
due to a single short wireless message. This was only
one of the numerous incidents where it served to save
not only property, but lives as well.

The achievement that astounded the world came shortly
afterward, taking place on March 27, 1899, when Marconi
successfully communicated between Dover on the British
side of the English Channel and Wimereaux on the French
side, a distance of 30 miles. The first application of wire-
less telegraphy to the Navy was made during the British
Naval Manoeuvres in 1899. Three cruisers were equipped
with the necessary apparatus, and a record distance of
85 miles was covered, when one of the ships received her
orders from the flagship of the fleet at that distance.
Immediately after followed the introduction of wireless
telegraphy in America, when Marconi superintended the
reporting of the International Yacht Races at New York,
where in less than five hours more than four thousand
words were despatched between the ship carr)ang the
apparatus and the shore station, from whence the mes-
sages were transmitted over line wires to "the New York
Herald,

Notwithstanding the continued success of the system,
it was 1 901 before any serious effort was put forth to
establish it commercially, and it was then decided by
the Marconi Company not to sell the instruments out-
right, but to lease them. Stations were set up along the

DIFFERENT M/tKES OF EQUIPMENT 191

Atlantic seaboard both in America and in England, and
these formed a comprehensive system of shore stations
commanding the most important shipping routes. Through
a deal with Lloyd's the Marconi Company secured a
contract in which the former are bound not to use any
other system for a period of fourteen years, and not to
communicate with ships equipped with any other appara-
tus than the Marconi. Thus an agreement was reached
that has effectually prevented any other company from
competing in the wireless transmission of messages be-
tween ships and shore stations of the trans-Atlantic fleet.
At the present time the ordinary ship and shore sta-
tions of the Marconi Company employ induction coils
giving a spark of 10 or 12 inches; these arc fitted with
vibrating-spring interruptors operated by the core of the
coil, and a key with large contact-points having a con-
denser shunted around them. The oscillation system of
the transmitter has long since been changed from a simple
open circuit to a compound loose-coupled circuit, though
occasionally a close-coupled system is used. The induct-
ance coil and high-potential transformer are mounted
distinct from the Leyden-jar battery, which is made up
of a dozen ^-gallon jars. Both the old and the new style
receptors are installed in each station, that is, the coherer
and Morse-register receptor and the magnetic detector and
telephone receiver apparatus, either of which may be used
as desired. In either case the aerial wire is connected
to the detectors through a closed circuit by a high-
frequency transformer or jigger. An adjustable induct-

192 DIFFERENT MAKES OF EQUIPMENT

ance coil and variable condenser having sliding contacts
permits the receiver to be tuned. The coherer and
Morse register receptor, though installed, is seldom used
now, for the magnetic detector receptor, owing to its
extreme simplicity, its accuracy, and its speed, has vir-
tually replaced the other and more complicated one.

The Telefunken System. — ^In the preceding historical
retrospect it was mentioned that certain experiments in
the very beginning of Marconi's success were witnessed
by Dr. Adolph Slaby, a professor at that time in the
Technical High School in Berlin. Mr. Fahie, in his
admirable work A History of Wireless Telegraphy,
gives some valuable points bearing on the origin of what
is now known as the Telefunken system. He says that
on Slaby's return to Germany after witnessing Marconi's
experiments in England, the former, in September, 1897J
engaged in some very instructive experiments in the
vicinity of Potsdam, first between the Matrosenstation
and the church at Sacrow, 1.6 kilometers, and then be-
tween the former place and the castle at Pfaueninsel,
3.1 kilometers. Other experiments followed at which the
Emperor of Germany was present and who, being im- !
pressed with what he had seen, put a number of sailors
and the large royal gardens at Potsdam at his disposal. \
The experiments which followed took place at the Naval
Station, where the receiver was located, and Peacock
Island, where the transmitter was set up. Continuing his
researches, he proceeded early in October to make some
tests over an open stretch of country free from all inter-

*. :

I.J I

DIFFERENT M/tKES OF EQUIPMENT 193

veiling obstacles, between Rangsdorp (sending station)
and Schonerberg (receiving station), a distance of 21
kilometers; the aerials used were made of double tele-
phone wires, and these were raised by captive balloons to
a height of 300 meters. It is reported that under these
conditions the communications were always clear and
accurate.

Dr. Slaby now coUoborated with Count Georg Arco,
and in the next two years they had built up a system
using a close-coupled oscillator and resonator which
they described shortly after Marconi made known his
compound system, or, to be more exact, in 1900. Their
apparatus took on a definite form, in which the inductance
coil was woimd around the case containing the Leyden
jars, and a mercury-turbine interruptor was substituted
for the vibrating-spring interruptor. This system was
adopted by the German Navy, and was exploited by the
AUgemeine Electricitats- Gesellschaf t (General Electric
Company) of Berlin..

About this time Prof. Ferdinand Braun of the Uni-
versity of Strassburg, Germany, brought out a tuned
system in which the open and closed circuits were loosely
coupled through the medium of a high-potential trans-
former, and this gave rise to another system; Prof.
Braun's arrangement was taken over by the Siemens and
Halske Company of Berlin, and equipments were in-
stalled in many places throughout Germany.

The patents of the Slaby- Arco people and the Braun
interests seemed to conflict, and in 1903 the feeling became

194 DIFFERENT MAKES OF EQUIPMENT

SO intense that a test of the merits of each faction was
aired in the German courts. After this unprofitable
procedure it was deemed advisable to amalgamate the
companies, and so the Slaby-Arco and the Braun-Siemens
and Halske systems were taken over by the Gesellschaft fur
Drahtlose Telegraphie (Wireless Telegraph Company) of
Berlin, and the equipment designated by a name that
Dr. Slaby had always favored, that is, "spark-telegraphy,"
or, as it is called in German, the Telefunken system.
This make of apparatus is sold outright, and the Bureau
of Equipment of the United States Navy has purchased
a large number of sets. The instruments this company
are sending^ out are beautifully finished, but are more
complicated than those of any of the other systems now
in use in the United States, for the reason, as a reference to
the wiring diagrams will show, that the transmitter is
furnished with a mercury-turbine interruptor, a motor for
its operation, and a magnetic blowout for the key, while
the receiver still retains the earliest form, having the
coherer, relay, tapper, and the Morse register. The
latter arrangement, slow as it is in operation, is preferred
by some to a receptor using an auto-detector and tele-
phone receiver, for the former records the messages on
a tape and therefore leaves no possibility for error on
the part of the receiving operator.

The Signal Corps, U. S. A., Portable System.— This
set has been developed chiefly through the efforts of
Major George O. Squire, and Major Charles M. Saltz-
man of the Signal Corps, U. S. A. The source of energy

Fig. 109.— U. S. Army Portable Wireless Set.

DIFFERENT MAKES OF EQUIPMENT ^o$

consists of a small direct shunt-wound generator geared
to oppositely disposed cranks all of which are mounted
on a knock-down tripod as sHown in Fig. 109. The
men can easily drive this dynamo at a speed of 1450
revolutions per minute when it will develop 6 amperes

Fig. 110.— U, S. Anny Portable Set Packed for Transportation.

at 30 volts. The generator complete weighs 86 pounds.
If desired a storage battery weighing 100 pounds may be
used in place of the hand generator.

The sending apparatus includes the generating unit
just described; an induction coil with interruptor; a
primary condenser; a sending key; a tuning-coil; spark-
gap; control switch, and the condensers for the secondary

2o6 DIFFERENT MAKES OF EQUIPMENT

circuit. The receptor includes a tuning coil; a crystal
detector; receiving condenser; pair of head telephone
receivers; two small dry cells; potentiometer; control
sw^itch and battery switch. The total weight of the
boxes containing the transmitting and the receiving
apparatus is 155 pounds.

The apparatus is so designed that it can be packed in
two chests, Fig. no, the weight being evenly distributed
on the sides of a mule. The total weight of the outfit
is 440 pounds, the jointed hollow wooden mast, previously
described in Chapter V, weighing 155 pounds. The
set has a range of about 25 miles over level country under
favorable atmospheric conditions while the distance
it will cover over mountainous country is a little more
than half the above figures.

A field staff of six men formed of two or three non-
commissioned officers and the others privates, are required
to set up the apparatus and to operate it. With trained
men the station may be set up in less than half an hour.
These portable sets have been assembled by the Signal
Corps in Washington, the individual parts being pur-
chased from various companies.

The United System. — ^This system is a composite one
and has been built up by a number of designers. It is
controlled by the United Wireless Telegraph Company of
New York City. This company was formed in 1907 for
the purpose of merging the Marconi and the De Forest
Wireless Telegraph Companies. In this it was not
successful, though it did acquire the rights of the latter

Fic. III.— Marconi Transatlantic Cableless Station at Glace B

DIFFERENT MAKES OF EQUIPMENT 209

company and equipped many coastwise vessels and
operated a number of stations along the Atlantic and
Pacific seaboards and on the great lakes. This company
was one of the first, if not the first, to use a crystal recti-
fying detector. 1

* Since the above was written the Marconi Company has acquired the
United Wireless Telegraph Company.

CHAPTER XI
SUGGESTIONS TO OPERATORS

General Infonnation. — ^The Marconi system is oper-
ated in conjunction with the Western Union Telegraph
Companies in the United States, with the Postal Tele-
graph Oflftces in Great Britain, and with the Inland
Telegraph and International Cables throughout the
world. Operators on board ship can therefore accept
telegrams from passengers for transmission to any part
of the world. Through rates to all points are furnished
by the company to the pursers and operators of the ships,
and are simply the usual land telegraphic rate plus the
wireless or sea rate.

Telegrams from persons on shore to passengers on

ships should be addressed in the following manner: (i)

name of passenger, (2) name of ship, and (3) name of

shore station through which it is desired to communicate^

thus:

John R. Collins,

Steamship Lucania,

Sagaponack Wireless Station.

210

212 SUGGESTIONS TO OPERATORS

Operators should despatch telegrams strictly in the order
received from the public, and as the time of communica-
tion is at present naturally limited, no time must be
wasted. Fig. 112 is a reproduction of the obverse side of
a wireless telegram form. A receipt for the sum charged
for each message is given on board ship by the purser
or operator, and on shore, subject to the usual conditions
exacted by the collecting office. These conditions apperr
on the reverse side of the telegram form, Fig. ii3,and the
operator should have the person who sends the message
sign it.

Should any telegram that is accepted by or to any of
the associated companies' stations fail to reach its destina-
tion and the non-delivery is proved to be in any way due
to negligence on the part of the company's employees^
the amount paid will be refunded to the sender when he
presents the receipt for the sum paid.

Rates for Wireless Messages. — ^Wireless communica-
tion is now open through the new Marconi station at
Sea Gate, Long Island, and New York Harbor. Mes-
sages may be sent to outgoing or incoming steamers when
they are down the Bay, or at any time when the vessels
are at a point between their docks and Babylon, Long
Island. The map shown in Fig. 114 indicates the location
of the Marconi marine service stations on the Atlantic
seaboard. Messages to outgoing and incoming steamers
can also be sent via Babylon, L. I., when ships are about
five hours from New York City; via Sagaponack, L. I.,
when eight hours from New York; via Siasconset, Mass.,

SUGGESTIONS TO OI'ER^TORS

Ifs

I ill?

■ Ifli

214

SUGGESTIONS TO OPERATORS

when fourteen hours out; and through Sable Island, via
Camperdown, Nova Scotia, when forty hours from New
York. The rates for such messages are as follows: For

Fig. 114. — Marconi Stations along the Atlantic Seaboard.

ten body words, address and signature not included,
$2.00 is charged plus the land-line charges via Sea Gate,
Babylon, or Siasconset, and $4.00 and land charges via
Sable Island.
Messages destined for all Atlantic liners routed via

SUGGESTIONS TO OPERATORS 215

Sea Gate, Sagaponack, Siasconset, South Wellfleet or
Cape May may be filed at any office in the United States
of the Postal Telegraph Cable Company or the Western
Union Telegraph Company. Those routed via Sea
Gate or Sable Island can be filed at any office of the West-
em Union Company, the operators at these offices hav-
ing full instructions as to the sending of such messages.
Long-distance telegrams may now be sent to certain
ships carrying Marconi long-distance receiving apparatus
throughout the whole course of the voyage across the
Atlantic. These vessels can be reached at any time by
long-distance wireless during the entire voyage in either
direction. Messages for these ships must be filed at the
office of the American Marconi Company, 27 William
Street, or the Company's head office, 18 Finch Lane,
London. Messages from points outside of New York
to these vessels are sent to New York in care of the
Marconi Company.

How Ships are Located in the Atlantic Ocean. — With
all these liners crossing and recrossing the Atlantic Ocean
means must be provided so that the operator at any shore
station, or on board any ship, may be able to quickly
ascertain the position of any ship at any given time. To
enable them to do this, the Marconi Company furnishes
operators in charge of stations at the beginning of
every month with a communication chart, as shown in
Fig. 114. The chart measures 14 by 20 inches, and
should be framed and hung on the wall or kept within
easy reach.

2i6 SUGGESTIONS TO OPERATORS

Assuming that a message has been received at the
Sagaponack Station for transmission to the Cunard Liner
Umbria, the operator at the former looks on his chart to
ascertain the ship's whereabouts in the ocean lane; he
may find that it is several hundred miles out of the reach
of his station, but that the New York of the American
Line is, we will say, about midway between Sagaponack
and the Umbria. The operator then signals the New
York, and when this vessel responds he transmits the
message with instructions to repeat it to the Umbria. In
a like manner any ship in the entire Atlantic service can
be located and gotten in touch with. Toward the end of
the month the vessels may be found dropping behind their
schedule according to the communication chart, but this
is easily corrected by checking them off with a pencil and
the chart thus kept fairly accurate. A thorough study of the
chart reproduced will prove of much value to the operator
who desires a position with the Marconi Company.

Offices of the Marconi International Marine Communi-
cation Company, Limited

Head Office:

18, Finch Lane,

London, E.C., England.

American Office:

27 William Street,
New York City.

SUGGESTIONS TO OPERATORS

217

List of United States Navy Ships and Shore Stations
"^ and Type of Apparatus Installed.

The following table shows the number and type of
ships and shore stations of the U. S. Navy. Owing to the
large number of changes at present being made, and
because of the fact that a number of installations are
composite sets, the accuracy of the table is not vouched
for.

Telefunken

International Telegraph Construction Co

(Shoemaker)

National Electric Signaling Co. (Fessenden) .

DeForest

Marconi

Stone

Slaby-Arco

Massie

United Wireless Telegraph Co

Miscellaneous

Composite

Total

Ship.

Shore.

142

Total.

25
23
7
7
4
II
6
8

3
51

184

List of Wireless Telegraph Stations Controlled by
the United States Army. — The Signal Corps has stations
working at St. Michael, Alaska, and Safety Harbor,
Alaska, the latter being the landing point for Nome.
Wireless communication between these two stations was
established by the Signal Corps in August, 1904. Since
that time the service has been continuous, there not
having been a single day's interruption iq the transaction

2i8 SUGGESTIONS TO OPERATORS

of a large volume of business. The stations are equipped
with small power plants, in which gasoline engines are
the motive power, giving about three kilowatts effective
energy for operating the transmitting devices. The sys-
tem used in these stations is largely composite, most of it
having been originated and constructed by Captain L. D.
Wildman of the Signal Corps, who had charge of
them.

The Signal Corps have wireless stations at Zamboanga
and Jolo, Philippine Islands, which have the same
capacity and power as the Alaskan stations above named.
There are small stations for the use of the Coast Artillery
and local work at the following points: Forts Hancock,
Wadsworth, Wood, Schuyler, Trumbull, Michie, Terry,
and Wright, New York; Benicia Barracks, Fort Mason,
and Alcatraz Island, California; Forts Worden and
Flagler, at the entrance to Puget Sound. All of these sta-
tions are largely composite in their equipment, apparatus
having been purchased from various makers of wireless
apparatus. The stations at Forts Wright and Schuyler
are about one and one-half kilowatts, and have in the
past been generally in free communication with each
other, the distance being about loo miles.

Where to Apply for Positions. — ^Applicants for posi-
tions may communicate with the following:

Chief Engineer Marconi Wireless Telegraph Company
of America, 27 William Street, New York City.

Chief, Bureau of Navigation, United States Navy,
Washington, D. C.

SUGGESTIONS TO OPERATORS 219

Chief Signal Officer, United States Army, Washington,
D. C.

Beginners are preferred who have a fair working
knowbdge of electrical apparatus, and who can send and
read in both the ordinary Morse and the Continental
codes. Those wishing to enlist in the United States
Navy must meet the following requirements:

Department of the Navy,

Bureau of Navigation,

Washington, D. C.

1. A candidate for enlistment as an electrician for wireless teleg-
rapher must hav* a working knowledge of telephones, measuring-
instruments, call-bells, etc., and be able to connect up same to
batteries and make minor repairs to them. Familiarity with ordi-
nary telegraph instruments, while an aid in acquiring a working
knowledge of wireless telegraphic instruments, is not an essential
qualification for enlistment as a wireless telegraph operator.

2. Applicants for enlistment must be able to write legibly and be
good spellers.

3. Applicants will be enlisted as electricians, third class, at $30
per month, and, if practicable, given a course of instruction on some
cruising ship or wireless telegraph shore-station already equipped,
and as found qualified will be assigned to cruising-ships as needed,
either in charge of the station or as assistants to the electrician in
charge.

4. Men detailed as operators will be eligible to promotion to
higher ratings of the electrical branch when they qualify as opera-
tors, and have served the required probationary time under the regu-
lations, through the successive grades to chief electricians at $60
per month, when they prove their ability to take charge of the wire-
less telegraph station and interior communication on board ship and

have been assigned to duty.

(Signed) H. C. Taylor,

Chief of Bureau,

2 20 SUGGESTIONS TO OPERATORS

Any request made to the Bureau of Navigation, Navy
Department, Washington, D. C, in reference to entering
the naval service, will receive prompt attention. Receiv-
ing ships and recruiting stations are located throughout
the country, and recruiting parties make occasional visits
to the large and small cities. The Navy Department
has fitted out two schools for training wireless operators
for the Navy, giving preference to the man who possesses
some electrical knowledge. He is required to pass an
examination and is then enlisted for a term of four years
with the rate of third-class electrician and given a course
'A instruction at the Navy Electrical Class either at the
Navy Yard, New York City, or at Mare Island, California.
Upon application to the Bureau of Navigation, a booklet
containing full information will be sent free of charge.

Applicants for enlistment in the U. S. Army will find
the following circular of interest:

War Department,

Office of the Chief Signal Officer,

Washington, D. C.

Enlistment Circular.

The following information is published to answer, in general,
inquiries regarding employment or services in the Signal Corps ot
the Army. Civilians are not employed, but enlistments of desir-
able persons will be made as privates, and promotions to the higher
grades made on merit as vacancies occur and the soldier's qualifi-
cations, conduct, and service justify. Promotions are usually rapid
in the case of men of high character who show proficiency in special
phases of electrical or other Signal Corps work. The grades and
pay of enlisted men of the Signal Corps are as follows:

SUGGESTIONS TO OPERATORS 221

In U. S. Abroad

Master signal electricians, per month $75 . 00 $90 . (X)

First-class sergeants, * * * ' 40 . 00 54 • 00

Sergeants, ** ** 34.00 40.80

Corporals, ** ** 20.00 24.00

First-class privates, ** ** 17.00 20.40

Privates, ** ** 1300 15. 60

with a slight increase each month after three years' service. All
enlisted men, in addition to their regular pay, receive rations, quar-
ters, clothing, fuel, bedding, medicine and medical attendance,
when required.

Owing to the professional and technical nature of the service in
the Signal Corps, a large proportion of the enlisted men are non-
commissioned officers. The clothing allowance of a first-class pri-
vate is about $138.00 for one enlistment; of a corporal, about $141.00;
of a sergeant, about $141.00; and the portion of this not used in
purchasing clothing is paid to the soldier in cash on discharge.
When on detached service at a station where there are no troops,
as many of the Signal Corps operators are, the soldier draws $1.15
per day as commutation of rations and quarters. Every soldier
is privileged to deposit his savings with any army paymaster, and
for sums so deposited, for the period of six months or longer, will
be paid interest at the rate of 4 per cent per annum.

After thirty years' service a soldier is entitled to be retired, and
to receive monthly during life three-quarters of the regular pay he
was receiving at date of retirement, and in addition $9.50 per month
as an allowance for clothing and subsistence. Non-commissioned
officers not more than thirty years of age are eligible for examina-
tion after two years* service for commission in the line of the army.
Applicants for enlistment must be between 21 and 35 years of age.
They must be unmarried, of good antecedents and habits, and free
from bodily defects and diseases. They must be citizens of the
United States, or have made legal declaration of their intention to
become citizens of the United States, and must be able to speak,
read, and write the English language.

It is necessary that the applicant furnish a certificate of good
moral character, with particular reference to sobriety, and also his

222 SUGGESTIONS TO OPERATORS

experience, if any, as an electrician, telegraph operator, or lineman.
Enlistments are for three years. Recruits, as a rule, ^.re first sent
to one of the Signal Corps Schools of Instruction, where they remain
about six months, to fit them for duty in the United States, Philip-
pines, or Alaska, or wherever the exigencies of the service may
demand. These schools are located at Fort Wood, New York Har-
bor; Omaha Barracks, Nebraska; and Benicia Barracks, Cali-
fornia, where courses are given in telegraphy, including wireless,
military signalling, electricity, photography, line construction, gen-
eral instructions concerning the care and handling of Government
property, and rendering the necessary reports; handling moneys
received at military telegraph offices, as well as practical military
instruction covering the duties of a soldier. The opportunities
for making use of any special aptitude are most excellent, and
in many cases have led to rapid promotion and most agreeable
service.

Probably no other branch of the Government service gives its
men such an opportunity for travel and seeing the world. The
care and operation of a complete network of cable and telegraph
lines, and the installation of the fire-control system in the seacoast
defences, take them to all parts of the United States, the Philippine
Islands, and Alaska. Upon expiration of term of service the Gov-
ernment returns a soldier to the original place of enlistment, or
allows him in cash an amount sufficient to pay his transportation
there. If you desire to enlist, application in your own handwriting
should be made to this office, accompanied by the certificate above
referred to, and if satisfaciory you will be furnished instructions as
to the recruiting officer to whom to apply, etc.

Applicants must defray their own expenses to the place of enlist-
ment, as their fitness for milttary service can only be determined
by a physical examination.

(Signed) A. W. Greely,
Brigadier-General, Chief Signal Officer, U.S.A.

SUGGESTIONS TO OPERATORS 223

SERVICE REGULATIONS FOR COMMERCIAL

OPERATORS

Regulations to be Observed at all Stations

1. The Instrument Rooms are strictly private, no
strangers are allowed on the premises without a signed
permit from the Managing Director.

2. All papers, books, reports and messages are strictly
confidential.

3. No Engineer or Operator may vacate his post with-
out authority from the Head Office. Before leaving
the station, the retiring officer must make up his accounts
to the day of his leaving, and shall hand over all accounts,
papers, money and the property of the Company generally
to his successor, who shall give him a written receipt for
all he has received, and duly notify the Head Office.

4. The Staff at any station are under the authority
of the Engineer (or, in the case of a station where there
is no Engineer, the Operator in charge), who will be held
responsible for the working of his station, and the Com-
pany's interests generally at that station.

5. The instruments must never be left unattended during
working hours.

6. The General Report which is sent in weekly by every
land station, and at the end of the round voyage in the
case of a ship station, must be drawn up by the Officer
in charge only, and is strictly confidential.

224 suggestions to operators

Signs and Prefixes

In addition to the Signs and Prefixes appearing on the
"Authorized Code Signals" sheet, the following shall be
used:

1. Distress Signals, — Vessels in distress send, at short
intervals, the signal: —

■ ■■ wmwmwm ■■■(SOS).

As soon as a station perceives the signal of distress,
it must suspend all correspondence, and must not resume
work until it has made sure that the communication con-
sequent upon the call for assistance has been completed.

When a ship in distress adds, after a series of signals
of distress, the call-signal of a particular station, the duty
of answering the call rests with that station only. Failing
any mention of a particular station in the signal of distress,
every station which perceives the call is bound to an-
swer it.

2. Retransmission, — Messages to be retransmitted bear
the additional prefix ■■■■■■ which is prefixed to the
'' Official Instructions " in all messages received, and
subsequently forwarded by a wireless telegraph station.
Thus, a Government message requiring to be retrans-
mitted would bear the prefix ■■■■■■ ■■■(XS), and
so forth.

3. End of Work, — The end of work between ship and
shore is indicated by the signal ■ ■ ■ ■■ ■ ■■ (S K).

4. International Signalling Code, — The signal

■ ■■■■■ ■■■■ ■■■■■(PR B)] indicates that the station

SUGGESTIONS TO OPERATORS 225

calling wishes to communicate by means of the Inter-
national Signalling Code. This signal must follow the ordi-
nary call ; and its use, as a service signal, is prohibited, for
any purpose, other than that above indicated. Messages
in this code, addressed to a wireless telegraph station
for onward transmission are not translated by that
station.

5. Completion of Translation. — The signal ■■■■■■■
is used by the translating station to show that a trans-
lation has been completed, and the station is now ready
to receive further messages.

6. Reqiiest for Repetition, — The signal ■■■■■■■■
indicates a request for repetition of something not
understood, or request by translating operator for
receiving operator to repeat message. The signal

■ ■■■■■■■ ■■■■■ ■ ■■ (? W A), fo' owed by a certain
word in the transmitted message, requests the transmitting
operator to repeat what follows the word. In the event
of more than one word being required, the number
of words required would come after ■ ■ m ■■ ■ ■ ^ thus:

■ ■■i"""«3""i""»"i In the event of the whole of
the message being required, the receiving operator would
say ■■■■■■■■ all.

7. Reply to a Service Message. — Service messages
which are replies to other Service messages are prefixed
BQ(-.-. ---H-

8. Clear Signal. — When all work has been transmitted,
and the operator has nothing on hand, he may give the
signal N N (■■ ■ ■■ ■).

226 SUGGESTIONS TO OPERATORS

9. All Correct. — For general use the signal O K
(■■■■■■ ■■■■■) signifies that all is right

10. How areSignals? — The signal H Q (■ ■ ■ ■ ■■■■■■■)
signifies to the receiving operator that the transmitting
operator wishes to know the quality of his signals.

Numbering of Messages

Every message shall bear a number.
Numbering shall begin at midnight and finish at mid-
night.

In the case of a transmitted message, the sender shall
number the message immediately before it is sent; in
the case of a received message, the receiver shall take the
number as sent by the transmitter.
Service messages will bear no number.
Great care must be taken to see that the message
numbers, either transmitted or received, are not duplicated.
Priority. — In all cases Government messages must be
sent first (except in the case of an urgent Service message),
private messages next, and press last.

The Order of a Message. — All messages shall be sent
in the following order:

ist. Prefix (Denoting the nature of the message).
2d. Number of the message.
3d. Station to (the station of its final destination) .
4th. Station from (the station where the message was

handed in).
5th. The number of words.
6th. The code time.

SUGGESTIONS TO OPERATORS

227

7th. The Break Signal ■■ ■ ■ ■

8th. The name and address.

9th. The Break Signal ■■ ■ ■ ■

loth. The text of the message.

nth. ■■■■■■■

1 2th. The Signature (if any).

13th. ■ Hi ■ ■■ ■

Timing of Messages

The following system of timing has been adopted, and
nust be strictly adhered to:

Flo. 115.— Timing Messages.

228 SUGGESTIONS TO OPERATORS

Explanation. — The hours from i p.m. to 12 midnight
comprise the alphabet from N to Z, the letter U being
omitted; the hours from i a.m. to 12 noon are denoted
by the first twelve letters of the alphabet, the letter J
being omitted.

If the letters are used singly, they show the hours only.
If they are used in combination they show the hours and
in addition a certain period of minutes.

Thus S denotes 6 p.m., S Q 6.20 p.m.

I denotes 9 a.m., I C 9.15 a.m., and o on.

Periods of less than five minutes are not taken into
consideration, thus: 9.52 p.m. would be coded as 9.5o>
but 9.53 P.M. would be coded as 9.55.

Transmission of Messages

1. Order of Transmission, — Between two stations,
radiograms of the same rank are transmitted separately
in alternative order, or in series consisting of several
radiograms, as may be determined by the coast station,
provided that the time occupied in the transmission of
any one series does not exceed 20 minutes.

2. Calling of Stations, and Transmission of Messages, —
I. As a general rule, it is the ship station which calls the
coast station.

2. The call must only be made, as a general rule, when
the distance of the ship from the coast station is less than
75 per cent of the normal range of the latter.

3. Before beginning to call, the ship station must
adjust its receiving apparatus to the highest possible

SUGGESTIONS TO OPERATORS 229

degree of sensitiveness and make sure that the coast
station which it wishes to call is not engaged in com-
•munication. If it finds that transmission is taking place
it awaits the first break.

4. The ship station uses, for calling purposes, the
normal wave-length of the coast station.

5. If in spite of these precautions the exchange of
public radiotelegraphic trafiic is interfered with, the call
must cease at the first request made by a coast station
open for public correspondence. This station must then
indicate approximately how long it will be necessary to
wait.

6. The call comprises the signal ■■■■■■■■, the call-
signal of the coast station thrice repeated, the word " de "
followed by the call-signal of the transmitting station
thrice repeated.

7. The station called answers by giving the signal
■■ ■ "1 ■ "i, followed by the call-signal of the calling
station thrice repeated, by the word ** de," by its own
call-signal, and by the signal mmmwm

If a station called does not reply as the result of the call
thrice repeated at intervals of two minutes, the call can
only be renewed after an interval of half-an-hour, the
station making the call having first ascertained that no
1 radiotelegraphic communication is in progress.

8. As soon as the coast station has answered, the ship
' station makes known :

(a) The distance of the ship from the coast station
in nautical miles.

2 so SUGGESTIONS TO OPERATORS

(b) Its true bearings in degrees reckoned from o to 360.

(d) Its speed in nautical miles.

(e) The number of words which it has to transmit.

9. The coast station replies by indicating the number
of words which it has to transmit to the ship.

10. If transmission cannot take place at once the coast
station informs the ship station approximately how long
it will be necessary to wait.

These details should be comprised in a service message?
which will always be the first message exchanged between
ship and shore.

When a coast station received calls from several ship
stations, the coast station decides the order in which the
ship stations shall be allowed to transmit their corre-
spondence.

The sole consideration which must govern the coast
station in settling this order is the necessity of allowing
every station concerned to exchange the greatest possible
number of radiograms.

Before beginning the exchange of correspondence, the
coast station informs the ship station whether transmis-
sion is to take place in alternate order or in series; it then
begins transmission or follows up these service instruc-
tions with the signal ■■ ■ "i (invitation to transmit).

The transmission of a radiogram is preceded by
the signal ■■■■■■■■ and terminated by the signal
■ Hi ■ ■■ ■, followed by the call-signal of the transmitting
station.

SUGGESTIONS TO OPERATORS 231

When the radiogram to be transmitted contains more
than 40 words, the transmitting station interrupts trans-
mission after each series of about 20 words with a mark
of interrogation ■■■■■■■■, and only continuous trans-
mission after having obtained from the receiving station
the repetition of the last word duly received, followed
by a mark of interrogation.

In the case of transmission by series, an acknowledg-
ment of receipt is given after each radiogram.

11. 'WTien the signals become doubtful, it is important
that recourse should be had to all possible means for
effecting transmission. For this purpose the radiogram
is repeated at the request of the receiving station, but not
more than three times. If in spite of this triple trans-
mission, the signals are still unreadable the radiogram is
cancelled. If an acknowledgment of receipt is not received
the transmitting station again calls the receiving station.
If no reply is made after three calls, transmission is not
continued.

12. If the receiving station, in spite of defective
reception, thinks that the radiogram may be delivered,
it inserts the service instruction " Reception doubt-
ful "at the end of the preamble, and sends on the
radiogram.

13. Operators are prohibited from exchanging super-
fluous signals and words. Trials and practice are only
permitted at stations in so far as they do not interfere
with the service of other stations.

14. All stations are bound to exchange traffic with the

2 32 SUGGESTIONS TO OPERATORS

minimum expenditure of energy required for obtaining
effective communication.

3. Maritime Intelligence. — All maritime intelligence
relating to casualties, derelicts, overdue vessels, etc.,
either reported to the station by vessels, or otherwise
coming to the knowledge of the officer in charge of the
station, must be immediately telegraphed to '* Lloyds,
London." It is essential that no information of this
character be communicated to any person, firm or cor-
poration other than Lloyds.

Copies of Messages

Messages received for deUvery shall be written in
duplicate by means of a carbon.

The carbon copy shall be handed to the addressee, and
the top copy retained. A message received for retrans-
mission need not be written in duplicate.

All messages received, sent, or retransmitted, shall be
filed away in numerical order at the end of each day's
working.

Acknowledgment of Receipt

The acknowledgment of a message, or a batch of mes-
sages, should be preceded by the call-signal of the trans-
mitting station, and followed by the call-signal of the
receiving station.

The end of work between two stations is indicated by
each station by means of the signal ■ ■ ■ ^ ■ ^ followed
by its call-signal.

SUGGESTIONS TO OPERATORS 233

The Check

At the end of each communication, and, in the case of
fixed stations, at the end of the day's work, the number
of messages and service messages received and sent shall
be checked.

This should be effected in the following manner:

Check. Sent lo.

Received i8.

The station receiving this should, if correct, reply in the
following manner:

Check. Sent i8.

Received lo.

This check must be made when all work has been
transmitted.

Checking of Cipher Messages, etc.

Messages in cipher should be carefully checked in the
following manner:

The receiving station shall, when he has received the
whole of the message, repeat it back, group by group,
the transmitting station carefully checking each group
from his written message.

Groups of figures appearing in messages, doubtful
words, and commercial marks, should also be checked
by the sender repeating the group or word (in abbreviated
form in the case of figures) immediately after the signal

234 SUGGESTIONS TO OPERATORS

In receiving a message it is essential that Operators
should be, as far as possible, absolutely satisfied of the
correctness of the message, and no pains should be spared
to obtain corrections and repetitions when necessary.

Regulations Respecting Messages Received from
THE Public or from Other Companies or Systems

1. The address of radiograms for ships at sea must be
as complete as possible; they must include the following:

(a) Name of addressee, with further particulars if

necessary.

(b) Name of ship in full, supplemented, in the case

of ships bearing the same name, by the nation-
ality of the ship.

2. All messages must be fully paid before being trans-
mitted. Lists giving tariffs of all systems will be sup-
plied to each station.

3. All messages received from the public, or from any
other telegraph system, must be written distinctly, and in
the case of messages handed in by the public, must bear
the name and address of the sender. Should the Operator
have any difficulty in reading a message for transmis-
sion, he may ask the sender to re-write it or explain the
doubtful portion.

4. The Operator shall give the sender of a message which
complies with all the regulations, a receipt for the amount
paid in full.

SUGGESTIONS TO OPERATORS ^35

5. Wording of Messages. — Messages may be written in
plain language, code language or cipher.

6. Plain Langimge. — Messages in plain language are
those composed of words or figures which convey an
intelligible meaning in one of the recognized languages.

7. Code Languages. — Messages in code languages are
comprised of real words not forming comprehensible
phrases, or of groups of letters which can be pronounced
and have the appearance of real words. The recognized
languages from which the words may be drawn are the
following:

English,

French,

German,

Italian,

Spanish,

Portuguese,

Dutch,

Latin,

•

Combinations formed by running together of two or
more words are not permissible.

8. Cipher. — Composed of groups of .figures or letters
having a secret meaning.

9. Charging. — In messages in plain language, the
number of letters allowed to a word is 15. Words con-
taining more than 15 letters up to an additional 15 letters
are charged as two words. In all telegrams, every iso-
lated letter or figure is charged for as one word.

10. Code Messages. — Code words are charged at 10
letters to a word.

11. Cipher Messages. — Letters or figures in cipher are
charged 5 figures or letters to a word.

12. Evasions. — Words incorrectly spelt so as to reduce

23^ SUGGESTIONS TO OPERATORS

the number of letters below the maximum, or incorrectly
joined together contrary to the usage of the language, are
inadmissible.

13. Compound Words, — Ordinary compound words, and
names of places, ships, towns, countries, provinces, family
names, written without a break are counted, as single
words, but if joined by a hyphen, or separated by an
apostrophe, they are counted as §0 many separate words.

14. The " Station to '' of any message, whatever its
length, is charged as one word.

Messages not Accepted for Transmission
The following are not admitted :

(a) Telegrams with prepaid replies.

(b) Telegraph money orders.

(d) Telegrams " to follow.''

(e) Paid service telegrams, except as regards trans-

mission over the ordinary telegraph system.

(f) Urgent telegrams, except as regards transmission

over the ordinary telegraph system.

(g) Telegrams to be delivered by express or by post.

In the transmission of radiograms from ship stations to
coast stations the date and time of handing in are omitted
from the preamble.

On retransmission over the ordinary telegraph system,
the coast station inserts, as the indication of the office of
origin, its own name, followed by that of the ship, and gives
as the time of handing in, the time of receipt.

SUGGESTIONS TO OPERATORS ^37

American and Canadian Counting and Charging

The charging and counting of inland messages in the
United States and in Canada are calculated as follows:

1. A good and sufficient address (which must include
the name of the State and Province) and the signature,
which may include a title such as President or Managing
Director, are transmitted free of charge.

2. The charge made is determined from a minimum
toll which covers the address, text and signature of a
message having a text of lo words or less, plus a further
toll for any additional words beyond lo in the text, cal-
culated at a uniform rate per word, the tolls and rates are
fixed by the liners over which the message passes, and will
be found in the Tariffs.

3. Dictionary words, initial letters, surnames of per-
sons, names of cities, villages, states, or territories, or
Canadian provinces, are counted and charged as one
word. Abbreviations of the names of towns, villages,
states, territories, or provinces, are counted and charged
as written in full.

4. Abbreviations of weights and measures in common
use are counted and charged as words.

5. All pronounceable groups of letters when not com-
binations of dictionary words are counted and charged
each group and word. When such groups are made up
from dictionary words, each dictionary word is counted
and charged as a separate word.

6. Figures, decimal points, bars of divi3iQn and letters

238 SUGGESTIONS TO OPERATORS

(except as in paragraphs 4 and 5, in groups or singly,
are each counted and charged as one word.

7. In ordinal numbers, the affixes st, nd, rd, and th, are
each counted and charged as one word only.

Reports, Logs and Abstract Sheets

Daily Logs, — Each station is supplied with a log book.
The logs must be carefully filled up and sent to the Head
Office.

In the case of land stations they shall be sent in daily,
in the case of ship stations they shall be sent in at the end
of the round voyage, together with the abstract sheets
and reports.

The General Report,- — ^This report must be made up by
the Officer-in-Charge of the station only, and is strictly
confidential. It should contain, in full, details of working
for the week or voyage and any suggestions which the
Officer-in-Charge may think likely to forward th^ Com-
pany's interests.

The Technical Report, — ^This report must contain full
details of the state of the installation. Any faults, or
accidents (with details of how they were rectified), must
be fully described; also any additions or alterations
which the Engineer or Operator-in-Charge may consider
advisable.

Abstract Sheets. — ^These sheets must be carefully filled
up and checked.

In the case of a ship station they shall be sent to the

SUGGESTIONS TO OPERATORS 239

Head Office immediately the ship completes the round
voyage.

In the case of a land station they shall be sent in at the
end of each month.

By order,
The Wireless Telegraph Company, Limited,

Secretary.

Instructions to Govern Communication between
Wireless Telegraph Station and Ships.

For Naval Operators.

I. A vessel wishing to communicate with a station and
having ascertained by listening in that she is not interfer-
ing with messages being exchanged within her range
should make the call letter of the station at a distance
not greater than 75 miles from it.

II. The call should not be continuous, but should
be at intervals of about three minutes in order to give
the station a chance to answer.

III. After the station answers the vessel should send
her name, distance from station, weather, and number
of words she wishes to send; then stop until the station
makes O. K. signals, the number of words she wishes
to send the vessel, and signals go ahead.

IV. Then the vessel begins to send her messages,
stopping at the end of each 50 words and waiting until
the station signals O. K. and go ahead; when all messages
have been sent she will so indicate If the sender desires

240 SUGGESTIONS TO OPERATORS

to designate the Western Union or Postal Telegraph
system for further transmission of his message, he should
do so immediately after the address, as, for example:
"A, B, C, Washington, D. C, via W. U. (or P. T.)."

V. When a vessel has indicated that she has finished,
the station will send to the vessel such messages as she
may have for her in the following order:

(a) Government business, viz., telegrams from
any Government Departments to their agents on board.

{b) Business concerning the vessel with which com-
munication has been established, viz., telegrams from
owner to master.

(d) Press dispatches.
{e) Other dispatches.

VI. In the case of the Nantucket Shoal lightship,
it will, immediately on receiving the vessel's call, acknowl-
edge, and (after receiving vessePs name, distance, weather
report, and number of words she wishes to send) transmit
the first three to Newport, and then tell the vessel to go
ahead with her messages.

VII. After receiving these and sending the vessel
any message on file for her, the lightship will transmit
to Newport messages received from the communicating
vessel in the following order:

(a) Government business.

(6) Urgent private dispatches, limited.

{c) Press dispatches.

{d) Other dispatches.

SUGGESTIONS TO OPERATORS 241

VIII. A naval wireless telegraph station has the
right to break in on any message being sent by a vessel
at any time, and the right of way may be given at any
time to a government vessel or one in distress.

IX. When two or more vessels desire to communicate
with a naval wireless telegraph station at the same time
the one whose call is first received will have right of way,
and the others will be told to wait and will be taken up
in turn. Vessels having been told to wait must cease
calling.

X. In case communication is not estabKshed with
any ship for which messages are on file, the naval wireless
telegraph station will notify the telegraph company
from which the messages were received, giving suflicient
information for them to identify the telegrams and notify
the sender.

XI. In order to obtain the best results both sending
and receiving apparatus should be tuned to wave length
of 320 meters.

XII. Until further notice the speed of sending should
not exceed 12 words per minute.

XIII. In order that all messages received at naval
wireless telegraph stations may be forwarded to ships for
which they are intended, and in order that all ships
equipped with wireless telegraph apparatus may receive
storm warnings, they should always report when in
signaling distance of a naval wireless telegraph station.

XIV. The service being without charge at present,
the Government accepts no responsibihty for the recep-

242 SUGGESTIONS TO OPERATORS

tion or transmission of messages from or for passing ves-
sels. Every effort will be made to transmit all messages
without error and as expeditiously as possible. It must
be remembered that errors are not uncommon in ordinary
telegraph and cable messages, so that due allowance
should be made.

XV. In order that the service may be made as good and
as useful as possible, it is requested that complaints
should be promptly reported to the Bureau of Equip-
ment as soon as possible after the cause therefor, giving
date, hour, and other details, to enable the Bureau to
investigate the case.

XVI. Information regarding the naval wireless tele-
graph service will be published in " Notices to Mariners."

By order of the Bureau of Equipment.

H. M. Hodges,
Commander y U, S, N., Hydrographer.

Distress Signals

Three calls for help are now used in wireless telegraphy
— two at sea and one on land. They are "SO S,"
*^ C Q D " and " S 5 S."

" C Q D," is the Marconi call that gamed prominence
at the time of the Republic disaster. " C Q " formerly
meant ''AH stations stand by!" The "D" was added
to denote danger. It consists of two dots, a space and
?. dot; two dots, a dash and a dot, a dash and two dots.

^' S 5 S » is, " S O S " in the Morse code, which is
used by land lines.

SUGGESTIONS TO OPERATORS 243

" S O S " is the international danger signal adopted
by the convention of wireless telegraph companies held
at Berlin in 1906. It is solely a call to be used in times
of distress to attract all stations on land and sea that
may be within reach. It is a simple call, consisting of
three dots, three dashes and three dots.

Wireless Call Book.

The Government Printing Office, Washington, D. C,
will send to any address on receipt of ten cents a book
giving the names, locations, call letters, wave lengths,
and makes of apparatus of all government and com-
mercial ships and shore stations.

CHAPTER XII

WIRELESS TELEPHONY

By Newton Harrison, E.E.,
Instructor of Electrical Engineering, Newark Technical School.

Wireless telephony difiFers from wireless telegraphy
in that speech is transmitted instead of the alphabetic
code. The character of the electric waves and the
means for generating them also difiFers from those em-
ployed in wireless telegraphy and which has been de-
scribed in the preceding chapters.

Forms of and Means for Producing Electric Waves.
— In the usual system of wireless telegraphy a series of
damped waves, as shown in Fig. ii6, and which arc
periodic in time are produced. In wireless telephony
it is necessary to employ sustained waves, the amplitude
of which is constant, as illustrated in Fig. 117.

There are three known and tested means for pro-
ducing the forms of electric waves as described above,
and these are :

(i) The Leyden jar or induction coil, the discharge
from either setting up electric oscillations which produce
waves of the first order.

344

iVIRELESS TELEPHONY

245

(2) The high-frequency alternating-current generator
which is capable of producing oscillations of the second

Fig. 116. — Damped Waves.

order and which have a periodicity of from 40,000 to
100,000 cycles per second.

Fig. 117. — Sustained Waves.

(3) The oscillation arc lamp, which also produces
oscillations of the second order and which has a fre-
quency of as high as 1,000,000 per second.

The General Method Employed. — Choosing one of
the two latter types of generators for producing con-
L.iidous and sustained oscillations, an aerial wire system
for converting the oscillations into electric waves and

?46 WIRELESS TELEPHONY

radiating them into space, and a telephone transmitter
for impressing on these waves the characteristics of the
voice, and which is graphically shown in the diagram,
Fig. ii8, the fundamental features of a practical wireless
telephone transmitter are presented.

The complementary apparatus for receiving the electric
waves includes an aerial wire system upon which the
waves impinge and which converts them into electric

Fig, ii8. — Voice Waves Impressed on Sustained Electric Waves.

oscillations, a detector by which a direct current is varied
by the oscillations, and a telephone receiver.

The Transmitter. — Since the high-frequency alternator
develops comparatively low frequencies and the oscilla-
tion arc lamp set up enormously high frequencies, and
hence is much more efficient as a generator of electric
waves, and, further, since the former is prohibitively
expensive and the latter exceedingly cheap, the arc
lamp will be chosen as the most suitable type of generator
for the transmitter to be described.

IV I RE LESS TELEPHONY

247

Specifically, then, a wireless telephone transmitter
comprises:

First: An arc lamp, usually fed by a direct current of
500 volts or more, with a shunt circuit around it con-
Condenser

Fig. 119. — Arc Light Oscillation Generator.,

Condenser

Fig. 120. — ^Arc Light Oscillation Generator and Electric- wave Emitter.

taining a variable condenser of low capacity, a variable
coil of high inductance, and which may be the primary
of an oscillation transformer, and a small resistance,
all of which is shown in Fig. 119.

248

IVIRELESS TELEPHONY

Second: An aerial connected to the secondary of the
transformer and in which oscillations are set up in virtue
of the mutual induction existing between the two coils,
as in Fig. 120.

Third: A telephone transmitter circuit containing a
source of electromotive force, and a primary coil, acting
upon the secondary and the terminals of which are
shunted across the arc lamp, the direct current being

E
</)

Inductance Coil

Fig. 121. — An Arc Light Wireless Telephone Transmitter.

prevented from flowing through the secondary by a
small condenser, as shown in Fig. 121. The arc lamp as
the real source of the operating waves must now receive
attention.

The Oscillation Arc. — ^That an arc lamp around
which is shunted an inductance and a capacity, as we
have seen, will produce electric oscillations was dis-
discovered by Rogers and Firth in 1893. That the
oscillations were continuous in time and sustained in
amplitude was discovered by Duddell in 1900, and, with

IVIRELESS TELEPHONY 249

Marchant, he further deduced important laws relating
to the production of these waves. The work of Duddell
bears the same relation to wireless telephony that that
of Hertz bears to wireless telegraphy. In 1903 while

Fig. 122.— The Collins Rotating Oscillation Arc.

experimenting with the singing arc Poulsen found that
if the arc burned in hydrogen the intensity of the oscilla-
tions are greatly increased.

Practical Application of the Arc to Wireless Telephony.
— ^The first practical application of the direct current

aso

WIRELESS TELEPHONY

arc to wireless telephony was made by Mr. Collins in
1900, and since that time he has devised many forms
of arc lamps for the production of sustained oscillations
and one of which is shown in the photograph, Fig. 122,
in the plan view, Fig, 123, and the side elevation, Fig. 124.
In this oscillation arc a pair of carbon or graphite disks

Fio. 123. — Plan View of the Collins Rotating Oscillation Arc,

are employed aa the electrodes and between which the
arc light burns.

The disks are mounted on parallel spindles, so that
they are in the same plane and are connected by means
of bevel gears to an insulated shaft. The disks are
insulated from each other by fibre bushings inserted in
the gearing, the casing forming one of the connections
while the insulated bearing in the bottom of the casing
forms the other. The gearing is so arranged that the

IVIRELESS TELEPHONY

carbon disks are rotated in opposite directions, the
power being furnished by a small motor.

Fic. 114. — Side Elevation of the Collins Rotating Oscillation Arc.

Theory of the Oscillation Arc. — Duddell ascertained
that an arc light will generate sustained oscillations only
when there is a small change in the potential difference
between the electrodes of the arc and when the corre-
sponding change in the current through the arc is numer-
ically greater than the resistance in the condenser and
numerically less than the resistance of the direct current
circuit in series with the arc.

The active or critical length of the arc must be main-
tained or oscillations will not be set up in the shunt

252 IVIRELESS TELEPHONY

circuit. This active length becomes greater as the cur-
rent increases, and it becomes less as the frequency
increases. If the value of the direct current is too large
then no oscillations will result. To obtain oscillations
of the greatest amplitude as high a voltage as possible
must be employed in the primary circuit feeding the arc.

Use of the Magnetic Field. — In his experiments
Poulsen placed the arc in a powerful magnetic field.
One of the advantages of this arrangement is that the
lines of force at right angles to the arc increases its
resistance and a higher initial voltage can be used than
would otherwise be possible. On opposite sides of the
Collins revolving oscillation arc a pair of electro magnets
are disposed and these not only increase the resistance
but serve to fix the arc at its critical length, and since
this is the resonant point in the closed circuit the oscilla-
tions are amplified and this means a greater radiation
of electric waves. A diagram of the primary circuit
which includes the magnets is shown in Fig. 125.

Resonance or Oscillograph Tubes. — Both open and
closed circuits may be tuned by any one of a number
of methods^ but a Collins resonance tube permits an
instant visual determination of the quantitative value
of the current and of the degree of resonance obtaining
in the closed and aerial wire circuits. It consists of an
exhausted tube into which two wires having a high
melting point and whose ends nearly touch are sealed.
Since the length of the light on the wires is proportional
to the current strength it becomes at once apparent when

IVIRELESS TELEPHONY

5.^

the circuits are in tune for when resonance obtains the
light on the wires is longest. One terminal of the
tube may be connected with any part of the oscillating

-h

Fig. 125. — Rotating Oscillation Arc with Oppositely Disposed

Electro-magnets.

circuit and the opposite end to a capacity. By means
of a rotating mirror the wave form of the oscillations
may be observed and it is easy to see if the oscillations
are periodic or sustained.

-^ I

254

TIRELESS TELEPHONY

High Tension
D.C. Generator^

Stop-up Auto
Trtnsformer

Condensers

•f 500 V.D.C. .a /^ B
Vfc- . I Jmc

Blow-out Magnet

Rotating Electrode
/Blow-out Magnet

-,^pwi

Rotating Elect ode ^ '

HHI

Condensers

Ground

Fig. 126.— Collins Wireless Telephone Transmitter.

Aerial

Auto
Transformer

Condenser

c «» I

CS C 'I , f

c
o

'Detector

Potentionnet^r

©^oly Cell
Receivers .

Ground

Fig. 127.

IV I RE LESS TELEPHONY 259

The Receptor. — Any receptor utilizing an electrolytic
or thermo-electric detector can be used to receive wire-
less telephone messages. The detector employed in the
system under consideration consists of two exceedingly
fine wires crossed at right angles and forming a thermo-
electric couple. Under the junction of these wires is
placed a resistance wire which is heated by the oscillatory
currents set up in the aerial wire system. A complete
wiring diagram of both the transmitter and the receptor
is given in Figs. 126 and 127, while photographic views
are shown in Figs. 128 and 129 of the complete system.

Tests of the Wireless Telephone. — The system of wire-
less telephony above described is the culmination of work
begun by Mr. Collins in 1899, and of the tests made with it
the Scientific American in its issue of Sept. 19, 1908, says:

'^The first of his series of tests took place between
his laboratory in Newark, where he has a high-power
sending station, and the Singer Building in New York
City, about twelve miles away, on the night of July 9,
when spoken words were clearly and loudly transmitted
across the intervening space. The following day the
distance was increased to thirty-five miles, when the
receiving station was located at Mr. Collins's country
home at Congers, N. Y., and then, amplifying the power
of the sending station and bringing the instrument into
sharp resonance, the Newark-Philadelphia tests were
made the following Tuesday at midnight, from the top
of the Land Title Building, a distance of 81 miles as
wireless waves travel.

APPENDIX

List of Books on Wireless Telegraphy,

A History of Wireless Telegraphy. By J. J. Fahie (England).
Published by Dodd, Mead & Co., New York. Price $1.50.
325 pages; 3 periods; 5 appendices; about 50 illustrations.

Every operator should read this book. It contains a
history of wireless telegraphy from 1838 to 1899; it covers
the subject thoroughly, and brings out the early work
of Marconi very fully. An appendix contains valuable
papers by Lodge, Branly, Hughes and others, as well as
a reprint of Marconi's first patent.

Signallittg Through Space Without Wires. (3d edition .) By Oliver
J. Lodge (England). Published by D. Van Nostrand Co.,
New York. Price 6 shillings. 133 pages; 9 chapters; 66 illus-
trations.

An account of the work of Hertz and the men who
succeeded him. As Hertz discovered the means to pro-
duce electric waves and to receive them, it behooves every
operator to learn of his work and to reverence him. The
book also contains the particulars of the first work done
along the line of tuning and syntonization.

Electric Waves. By Heinrich Hertz (Germany). English Transla-
tion by D. E. Jones (England). Published by Macmillan Co.,
New York. Price $3.00. 279 pages; 14 chapters; 40 illustra-
tions.

This book contains the classic papers of Hertz on his

researches on the propagation of electric action through

261

262 /1PPENDIX

space. It is of necessity a mathematical treatise, but
there are many portions that can be read with profit by
the ordinary operator. If possible, this he should do, for
the whole structure of wireless telegraphy rests on the
foundation laid by Hertz.

Les Applications Practiques des Ondes Electrics. By Albert Turpain
(France). Published by C. Naud, Paris, France. Price 12
francs. 412 pages; 6 chapters; 271 illustrations.

A French book that contains an account of the work
from 1897 to 1902, especially of the developments in
Europe during this period.

Modern Views 0} Electricity. By Oliver J. Lodge (England). Pub-
lished by the Macmillan Co., New York. Price $1.50. 422
pages; 15 chapters; 55 illustrations.

The object of this book is to explain without techni-
calities the most advanced thought on electrical subjects
at the present time. The work is divided into four parts,
i.e., (i) Electricity Under Strain; (2) Electricity in Loco-
motion; (3) Electricity in Whirling Motion or Magnetism;
and (4) Electricity in Vibration, or Radiation, commonly
called Light. All these are treated in a more or less popu-
lar manner, and are adapted to those who have some
acquaintance with the ordinary facts and phenomena of
electrical science.

Onde Hertziane e Telegrafo Senza FUi, By Oresta Murani (Italy).
Published by Ulrico Hoepli, Milan, Italy. Price 2 1. c. 341
pages; 9 chapters; 170 illustrations.

A popular treatise in Italian on wirelesss telegraphy.

LIST OF BOOKS ON IVIRELESS TELEGRAPHY 263

Wireless Telegraphy and Hertzian Waves. By S. R. Bottone
(England). Published by Whittaker & Co. 4th Edition.
136 pages; 39 illustrations. 1910.

Wireless Telegraphy for Amateurs and Students. By S. M. St.
John. Published by same, New York. Contains theoretical
and practical information together with complete directions for
performing numerous experiments in wireless telegraphy with
simple home-made apparatus.

Wireless Telegraphy, Signal Corps, U. S. Army. By Edgar
Russel. Fort Leavenworth, 1910. Principles of field and
station equipment. - .

Wireless Telephone Construction. By Newton Harrison. Pub-
lished by Spon & Chamberlin. New York, 1909. A compre-
hensive explanation of the making of a wireless telephone
equipment. 74 pages; illustrated.

Official List of Wireless Stations. Published by the International
Telegraph Bureau, Berne, Switzerland. List of stations open
for international trafiic and gives laws and regulations.

Handbook for Wireless Operators. Published for the Great Britain
Post Office by Eyre & Spottiswoode, Ltd., 1909. This handbook
is for operators working installations licensed by His Majesty's
postmaster-general.

Report on Wireless Convention. Ordered by the House of Com-
mons to be printed, 1907. Printed for H.M. Stationery Office
by Wyman & Sons, Ltd. Report for the Select Committee,
together with the proceedings of the committee, minutes of
evidence and appendix.

Conference on Wireless Telegraph, Berlin, 1906. Printed for H. M.
Stationery Office by Eyre & Spottiswoode. London. 1906.
French text with English translation. Copy of the Interna-
tional wireless convention, additional undertakings, final
protocol, and regulations signed at Berhn on the 3d day of
November, 1906.

Conference on Wireless Telegraph, Berlin, 1906. Printed by
Government Printing Office, Washington, D. C, 1907. Inter-
national wireless telegraph convention concluded between
Germany, the U S. of America, Argentina, Austria, Hungary,

264 APPENDIX

Belgium, Brazil, Bulgaria, Chile, Denmark, Spain, France,
Great Britain, Greece, Italy, Japan, Mexico, Monaco, Norway,
the Netherlands, Persia, Portugal, Roumania, Russia, Sweden,
Turkey, and Uruguay.

List oj Wireless Telegraph Stations. Published by Navy Depart-
ment, Bureau of Equipment, Washington, D. C. List of
wireless stations of the world including shore stations, merchant
vessels, and vessels of the U. S. Navy.

U. S. Navy Ship and Shore Station Plants. Published by Bureau
of Equipment, Navy Dept., Washington, D. C. Description
of wireless telegraph plants on board United States naval vessels
and at United States naval shore stations.

Wireless Operators' Pocket Book. By Leon W. Bishop. Published
by Bubier Publishing Company, Lynn, Mass. Contains in-
formation and diagrams.

Electric Waves. By H. M. Macdonald. Published by University
Press, Cambridge, England, 1902. Being the Adams prize
essay in the University of Cambridge.

Die Telegraphic ohne Draht. By Adolph Prasch (Germany).
Published by A. Hartleben, Leipzig, Germany. Price 8 marks.
265 pages; 2 parts; 202 illustrations.

Gives a description of the work done up to 1902; it
is printed in German and contains a few mathematical
formulae.

Die Telegraphie ohne Draht. By Agusto Righi and Bernhard
Dessau (Italy and Germany). Published by Friedrick Vieweg &
Sohn, Braunschweig, Germany. Price 16 marks. 481 pages; 1^
chapters; 258 illustrations.

This book is also in German and is much more preten-
tious than the preceding volume, besides bringing the
art up a year later, and up to and including Marconi's

LIST OF BOOKS ON IVIRELESS TELEGR/iPHY 265

experiments on the Carlo Alberta. The Marconi, Slaby-
Arco, and Braun-Siemens and Halske systems are very
fully treated.

La T^Ugraphie sans Fils, By Andre Broca (France). Publisl ed
by Gauthier-Villars, Paris, France. Price 10 francs. 234 pages;
12 chapters; 52 illustrations.

A simple treatise in French on electric waves and their
application to wireless telegraphy.

Wireless Telegraphy for Naval Electricians. By Commander S. S,
Robison, U. S. Navy. Published by the U. S. Naval Institute.
Annapolis, Md., 191 1. 212 pages. This manual, first pub-
lished in January, 1907, was revised in 1909 by L. W. Austin.
The present, (2) revision contains the results of som^ of Dr.
Austin's later researches.

Wireless Telegraphy: Its Origin, Development, Inventions, and
Apparatus. By Charles Henry Sewell (United States). Pub-
lished by D. Van Nostrand Co., New York. Price $1.50. 229
pages; in 4 parts; 85 illustrations.

The first book on wireless telegraphy published in the
United States. The author's aim was to present a com-
prehensive view of the subject, giving its history, prin-
ciples, and possibilities in theory and practice.

Wireless Telegraphy: Its Theory and Practice. By William Slaver
(United States). Published by The Maver Publishing Co., New
York. Price $2.00. 199 pages; 15 chapters; 121 illustrations.

Contains an account of all the wireless systems at the
time the text was prepared, and gives a theoretical and
practical statement, as free as can well be from formulae,

266 APPENDIX

written in a manner designed to be clear to the general
reader.

The Story of Wireless Telegraphy. By A. T. Story (English).
Published by D. Appleton & Co., New York. Price $i.oo.
215 pages; 12 chapters; 56 illustrations.

This is just what its name indicates — ^wireless teleg-
raphy from its earUest conception to 1904, told in the
simplest language.

Maxwell's Theory and Wireless Telegraphy. By Frederick K.
Vreeland (United States). Published by the McGraw Publishing
Co., New York. Price $1.50. 225 pages; 2 parts; 145 illus-
trations.

First part is a translation of Poincair^'s physical treat-
ment of Maxwell's theory — the latter being the basis of
Hertz's deductions and experiments — and its application
to some modem electrical problems. The second part
shows how the principles are applied to wireless telegraphy.

Wireless Telegraphy and Telephony. By Domenico Mazzotto
(Italian). Translated by S. R. Bottone (English). Published by
Whittaker & Co., London. Price 6 shillings. 415 pages; 12
chapters; 253 illustrations.

A clearly written work on wireless telegraphy, covering
the whole general scheme, together with a chapter on the
new art of wireless telephony.

Traits Elementaire de TeUgraphie et de TiUphonie sans Fil. By
E. Ducretet (France). Published by R. Chapelot & Co., Paris,
France. Price 3 francs. 89 pages; 7 chapters; 30 illustrations.

Principally devoted to a description of Capitaine E.
Ducretet's wireless telegraph and telephone experiments.

LIST OF BOOKS ON IVIRELESS TELEGRAPHY 267

Wireless Telegraphy. By S. W. de Tunzlemann (England). Pub-
lished by "Knowledge," London. Price 3 shillings. 104 pages;
8 chapters; 30 illustrations.

A popular exposition of the principles of wireless teleg
raphy.

Wireless Telegraphy and Hertzian Waves. By S. R. Bottone
(England). Price 3 shillings. 120 pages; 37 illustrations. 1900.

An attempt to set forth in simple language the ele-
mentary principles upon which wireless telegraphy de-
pends.

The A B C of Wireless Telegraphy. By Edward Trevert. Pub-
lished by Bubier Publishing Company, Lynn, Mass. Price 75
cents. 7 chapters; 20 illustrations.

A plain treatise on electric-wave signalling and the
theory, method of operation, and construction of various
pieces of the apparatus employed.

Wireless Telegraphy. By Gustave Eichhom (Germany). Pub-
lished by J. B. Lippincott Co., Philadelphia. Price $2.75.
116 pages; 11 chapters; 79 illustrations.

A mathematical treatise presenting the fundamental
principles of electric-wave action as applied to the Tele-
funken system of wireless telegraphy.

Wireless Telegraphy : Its History, Theory, and Practice. By A.
Frederick Collins of New York. Published by the McGraw
Publishing Co. Price $3.00. 299 pages; 20 chapters; 323 illus-
trations.

The first systematized work in any language on the
subject. Each chapter begins with a brief history of the
individual subject; it is then treated theoretically and

268 APPENDIX

mathematically; its experimental investigation follows, the
chapter finally closing * with the practical workings of
the apparatus. The chapter on Capacity^ Induction,
and Resistaftce defines these terms and explains their
effects on electrical oscillations; also how to calculate
the constants of an aerial wire, and how to measure the
capacity, inductance, and resistance values of aerial sys-
tems, all in simple and concise language.

The theory of the Induction Coil is fully treated, while a
separate chapter tells how to build coils from a half-inch
up to the largest sizes, giving sparks especially adapted to
wireless transmission. Twenty-five different kinds of
electric-wave detectors are explained and illustrated.
The chapters on Transmitters and Receptors classify
all the diflferent makes of apparatus, and in such a
way that the reader can instantly ascertain the charact-
eristic features of any one of the numerous systems
and wherein it is alike or different from those of any
other make.

In the chapter on Subsidiary Apparatus each specific
part of the complete equipment is minutely described and
illustrated, except Oscillators and Detectors, since these are
treated exhaustively in distinct chapters. For instance,
nine different styles of keys are considered; three different
types of condensers; high- and low -potential transformers;
decoherers; relays, ordinary and polarized; indicators,
including Morse registers, telephone receivers, and siphon-
recorders; as well as tuning-coils, choking-coils, polarized

LIST OF BOOKS ON IVIRELESS TELEGRAPHY 269

cells, screening boxes, and the alphabetic codes used in
wireless.

Aerial Wires and Earths, Resonance and Syntonization
are dealt with in separate chapters in all their phases, and
this is the only work containing the history, theory, and
practice of these hitherto Httle understood subjects. In
conclusion, the last chapter is devoted to Wireless Tele-
phony , and contains all the information, such as speaking

arcs, selenium cells, etc., that was available when the
book was written.

Making Wireless Outfits, By Newton Harrison. Published by
Spon & Chamberlin. New York, 1909. A concise and simple
explanation of the construction and use of an inexpensive wireless
equipment for sending and receiving up to 100 miles. 61 pages.

Electric Waves, By W. S. Franklin. Published by The Macmillan
Co., New York. An advanced treatise on alternating current
theory.

Principles of Electric Wave Telegraphy. By J. A. Fleming. Pub-
lished by Longmans, Green, & Co. London, 1908. The most
comprehensive work yet published on wireless telegraphy.
671 pages, and many illustrations.

Elementary Manual of Wireless Telegraphy and Telephony, By
J. A. Fleming. Published by Longmans, Green, & Co. 340
pages. For students and others.

Handbook of Wireless Telegraphy, By James Erskine-Murray.
Published by Crosby, Lockwood & Son. London, 1907. In-
tended for those who are already acquainted with the funda-
mental theory and practice of wireless telegraphy. 318 pages.

Radio-Telegraphy, By C. C. F. Monckton. Published by D.
Van Nostrand Company, New York. Devoted to the general
practice and principles of wireless. 272 pages.

Plans and Specifications for Wireless Telegraph Sets. By A.
Frederick Collins. Published by Spon & Chamberlin. New

2 70 APPENDIX

York, 191 2. In four parts. A practical book. Gives detailed
description and full working drawings for five different sizes of
wireless telegraph sets, which are capable of covering distances
of from J mile to one hundred miles. The plans and speci-
fications were drawn up under Mr. Collins* supervision and the
apparatus was constructed for them in his Newark laboratory.

GLOSSARY OF WIRELESS TELEGRAPH WORDS, TERMS,

AND PHRASES

Adjustable condenser. See Condenser.

Aerial. A word much used instead of the longer term aerial wire.

Aerial switch. A switch used to throw the aerial wire into connec-
tion with the spark-gap and out of connection with the detector,
and vice versa.

Aerial wire. The wire suspended from a mast, kite, or balloon, and
connected with the spark-gap when sending and the detector
when receiving. When sending it is often termed a sending
wire; also a radiator. When receiving it is sometimes termed
the receiving wire or receiving aerial; also an antenna. It may
be termed a vertical wire, whether sending or receiving. If
formed of one or two parallel wires it is termed a plain aerial;
if more than two parallel wires a grid; then there is the fan-
shaped aerial, cylindrical, inverted pyramid, and rectangular
aerials. Aerials are usually, but not always, open circuit, that
is they are insulated from everything and end abruptly at
the top. A closed-circuit aerial indicates that it forms a Jcop
at the top.

Air-gap. Wherever a high-tension circuit is broken and the con-
nection is made by a high -potential discharge sparking across
the gap the space is termed an air-gap or a spark-gap. Such
an arrangement is used to cut out the transmitter from the
receiving aerial, so that the received energy may not be dis-
sipated in the sending circuits.

Alternations. A current that changes its direction slowly, as pro-
duced by a commercial alternating generator, is termed an
alternating current; a current that surges through a circuit with

271

2 72 APPENDIX

high frequency is called an oscillating current; while a charge
monng to and fro rapidly enough to produce light is termed a
vibration.

Anode. The point or path by which a direct current enters the
electrolyte or other medium; it is the positive pole of the spark-
gap, but is used chiefly to indicate the fine point of an electrolytic
detector or the smaller terminal of an electrolytic interruptor.
The negative electrode is called the cathode.

Antenna. The receiving aerial — never the sending aerial; so called
from the feelers attached to the heads of insects, to which it is
likened in reaching out and receiving the electric impulses.

Barretter. A name given by Fessenden to his electrolytic detector.

Battery. Three kinds of batteries are used in wireless telegraphy:
i.e. (i) dry batteries j (2) storage batteries, and (3) Leyden-jar
batteries, i is used in the receiving circuit in connection with
the tapper and Morse register; 2 is sometimes used to supply
the initial energy for operating the induction coil, and 3 in the
high-tension circuit of the transmitter.

Battery circuit. Usually refers to the internal circuit of a receptor,
which includes the tapper and Morse register.

Bridle. A cord attached to a kite that holds the latter at the proper
angle in the wind; the kite-cord is attached to the bridle.

Brush discharge. See Discharge.

Buzzer. A vibrating arrangement like an electric bell, but without
the gong. The testing-box for the coherer is often called a
buzzer.

Capacity. Any object that possesses the property of being charged
with electricity; hence an aerial wire, a condenser, or a metal
plate are called capacities for short when this is meant.

Capacity cage. A cylindrical cage made of wire and placed at the
top of the aerial wire to give it additional capacity.

Cathode. The negative terminal of an electrolytic detector or an
electrolytic interruptor; it is always the larger terminal in
these instances. See Anode.

Circuit. Any electrical conductor through which a current can flow.
A low-voltage current requires a loop of wire or other conductor,
both ends of which are connected to form a continuous circuit;

GLOSSARY 273

this is termed a closed circuit. When the current is oscillatory
it will surge through a wire open at both ends; this is an open
circuit. Where a closed circuit and an open circuit are coupled
together they form a compound circuit. When the closed and
the open circuits are joined directly together they form a close-
coupled circuit; when they are joined through a transformer-
coil they form a loose-coupled circuit.

Circuit. The primary circuit of the transmitter and the circuit of
the receptor containing the dry battery are sometimes called
battery circuits; also low-voltage circuits; also local circuits;
also internal circuits.

Circuits. The open and closed circuits in which the oscillations of
the transmitter and the receptor surge are termed high-tension
circuits; also external circuits. The high-tension circuits of
the sender form the oscillation circuits, called for short the
oscillator \ the aerial-wire system of the receiver is termed the
resonator circuit or merely the resonator.

Circuits. A parallel circuit is one in which a number of circuits
have all their positive poles connected together; also termed a
multiple circuit. A series circuit is one through which tV.e
current passes without being divided; a continuous circuit. A
shunt circuit is a branch or additional circuit through which a
portion of the main current passes.

Closed circuit. See Circuit.

Compound circuit. See Circuit.

Close-coupled circuit. See Circuit.

Condenser. All conducting objects with their insulation form
capacities, but a condenser is understood to mean two sheets or
plates of metal placed closely together, but separated by some
insulating material, (i) When paper is used as the dielectric
it is termed a paper condenser; (2) where mica is used it is
, termed a mica condenser; and (3) where glass jars are coated
nside and out with tinfoil it is termed a Leyden-jar condenser^
o battery, because this kind was first made in Leyden, Ger-
many. When the capacity of t! e condenser can be varied it
is termed an adjustable condenser.

Convective discharge. Sec Disci. arc;e.

2 74 APPENDIX

Discharge, (i) A faintly luminous discharge that takes place from
the pointed positive terminal of an induction coil, or other
high-potential apparatus, is termed a brush discharge. (2) A
continuous discharge between the terminals of a high-potential
and high-frequency apparatus is termed a convective discharge,
(3) The sudden breaking-down of the air between the balls
forming the spark-gap is termed a disruptive discharge; also
termed an electric spark; also spark, which is even shorter.

Disruptive discharge. See Discharge.

Damping. The degree to which the energy of an electric oscillation
is reduced or lessened. In an open circuit the energy is damped
out very quickly, that is, in one or two swings; while in a closed
circuit it is greatly prolonged, the current oscillating twenty
times or more before the energy is dissipated.

Electrodes. Either of the ends or terminals immersed in the elec-
trolyte of either an electrolytic interruptor or electrolytic detec-
tor. Occasionally the terminals forming the spark-gap are
called electrodes.

Electric oscillations. A current of high frequency that surges through
an open or closed circuit, (i) An electric oscillation may be
set up by releasing a charged wire or other capacity by means
of a disruptive discharge; under these conditions, oscillations
not only have a high frequency, but a high potential. (2)
When electric waves impinge on an aerial wire or other resonat-
ing system, they are transformed into electric oscillations of a
frequency equal to those emitting the waves, but, owing to the
very small amount of energy received, the potential is very low.
(3) Prolonged or sustained oscillations are those in which the
damping factor is small; damped oscillations are those that
are quickly transformed into electric waves. See Damping.

Electric spark. See Discharge.

Electric waves. When an electric oscillation surges through a wire,
some of its energy is transformed into waves m the ether, very
much as an ordinary electric current is converted into magnetic
Unes of force (see Electric oscillations), (i) Free electric
waves are waves that are not guided by the conducting medium
of either metallic conductors or the earth's surface. (2) Sliding

QLOSS/fRY 275

electric waves are waves that slide along wires or the earth's
surface. (3) Trains 0} electric waves are a series of waves
sent out by constantly recurring electric oscillations due to a
succession of electric sparks.

Earth. A word used to indicate the place in which the aerial-wire
system forms a connection with the earth.

Earthed terminal. The wire connecting the plate buried in the
earth and the aerial wire; also used to indicate the wire with
the plate attached; also called a ground, also earthed connection.

External circuit. See Circuit.

Earth-plate. A sheet of metal or wire-netting used to form a con-
tact with the earth or water for the aerial- wire system.

Feeble oscillations. See Oscillations.

Frequency. The number of reversals of an electric current per
second, (i) A low- frequency current usually implies an alter-
nating current of commercial frequency. (2) A high-jrequency
current indicates a frequency which can only be obtained by a
disruptive discharge.

Ground. Used instead of " earth." See Earth.

Hertzian waves. Same as electric waves; so called after Hertz,
who discovered them.

High frequency. See Frequency.

High potential. See Potential.

High pressure. See Potential.

High-tension. See Potential.

High voltage. See Voltage.

Inductance. The characteristics of a circuit which cause the mag-
netic induction of a current to accentuate the value of its
electromotive force. It is the inductance of a circuit that
retards or holds back a current on making the circuit, and gives
it increased momentum on breaking the circuit which produces
the "extra-current'' effect. Self-induction is the inductive
effect of a current acting on itself that causes its electromo-
tive force to rise with an increasing or decreasing magnetic
field.

Inductance coil. A coil of wire used to provide additional inductance
for the aerial-wire system. Variable inductance coil is a coU

276 APPENDIX

arranged with plugs or clips, so that the value of inductance
may be changed.

Induction. See Mutual Induction.

Interference. The crossing of two trains of electric waves that
tends to diminish or increase the intensity of the other. It is
the untoward interference between electric waves from different
station? that makes selective signalling so difficult a problem.

Internal circuit. See Circuit.

Jigger. A name given by Marconi to a small oscillation -trans-
former

Juice. A vulgar word much used by operators and others for elec-
tric current.

Kinetic. In motion or active; opposed to static or stored-up
energy; an electric current is kinetic; a charge is static.

Leyden-jar battery. Two or more Leyden jars coupled together.

Local circuit. See Circuit.

Loose-coupled circuit. See Circuit.

Low frequency. See Frequency.

Low potential. See Potential.

Low tension. See Potential.

Low voltage. See Voltage.

Maximum. The greatest quantity, amount, or degree attainable.

Mica. A mineral that may be split into thin transparent or trans-
lucent sheets, forming a most excellent insulation; sometimes
called isinglass.

Micanite. A compound having mica for a basis; it can be moulded
into any form or shape desired. Largely used for insulating
tubes between the primary and secondary of induction coils.

Minimum. The smallest quantity, amount, or degree attainable.

Mutual induction. Induction produced between two circuits in
proximity with each other by the mutual interaction of their
magnetic fields.

Non-inductive resistance. A coil of wire wound double, starting
with the loop: such a coil possesses resistance but not induc-
tance. See Resistance.

Ohmic resistance. See Resistance.

Open circuit. See Circuit.

GLOSSARY 277

Oscillation. See Electric Oscillation.

Oscillator. A circuit designed especially for oscillating currents.

Oscillator balls. The balls of the spark-gap.

Oscillation circuit. See Oscillator

Parallel circuit. See Circuit.

Period. The time that elapses between two successive phases of
an oscillation.

Plain aerial. See Aerial.

Potential. Electrical energy under pressure but not in motion.
Ordinary or low potentials aie those at the terminals of com-
mercial generators; high potentials are produced by induction
coils and similar devices. The word tension is used synony-
mously with potential. See Voltage.

Radiator. The aerial wire when connected with the sending appara-
tus.

Radiator system. The aerial-wire system and other high-tension
circuits of a transmitter.

Rat-tail. The wire connecting the aerial wire with the sending or
receiving apparatus.

Receiving aerial. See Aerial.

Receptor. A term proposed by the author for the entire receiving
apparatus; the purpose was to differentiate the receiving ap-
paratus as a whole from the telephone receiver, which is more
often called simply a receiver.

Resistance. That property of an electric circuit which opposes or
resists the passage of an electric current. The ohmic resistance
of a circuit equals the electromotive force divided by the cur-
rent. See Non-inductive Resistance.

Resonator. The aerial- wire system and other high-frequency cir-
cuits of a receiving apparatus; also resonating system.

Rheostat. A resistance to cut down the current; an adjustable
resistance is one that can be varied within certain limits.

Ruhmkorff coil. Same as induction coil; so called from Ruhm-
korff, who built the earliest practical coils.

Selective. When two or more messages sent at the same time can
be received without interference, the systems are said to be
selective. See Interference; Tuning; Syntonic.

278 APPENDIX

Shunts. Resistances for altering the sensitivity of a hot-wire am-
meter or other instrument.

Spark. See Discharge.

Spark-balls. Same as oscillator-balls.

Spark-gap. The space between the terminals of the secondary of
an induction coil where the disruptive discharge or spark takes
place.

Static. Electricity at rest; opposed to kinetic.

Striking distance. The distance the spark passes between the
oscillator-balls.

Syntonic. When a sending and a receiving station are each ad-
justed to a certain wave-length, they are said to be syntonized,
or in syntony with each other; as, a syntonic system. See
Tuned; Selective.

System. The connection or manner of arrangement of parts of the
sending and receiving apparatus as related to the whole, or the
parts so related collectively, as the aerial- wire system.

Time-constant, (i) The time counted from the instant of closing
an electric circuit which the current requires to rise to about §
of its maximum value. (2) The time required for the charge of
a condenser, or other capacity to fall to about half its maximum
value. (3) High time-constant: wjjien the time required for
a certain function of either electrical or mechanical action takes
longer than half of its mean time. Any constant movement
that is relatively slow is said to have a high time-constant. (4)
Low time-constant: when the time required for a given function
of either electrical or mechanical action takes less than half of
its mean time; any constant movement that is relatively rapid
is said to have a low time- constant.

Transformer. A primary and secondary coil for stepping up or
down a primary alternating current. The term indtiction coU
is used to mean a coil using a direct primary current, and con-
verting this into alternating currents of higher potential by
means of an interruptor (see Induction Coil). A transformer
requires no interruptor, since the initial current is alternating.

Tuning. When the open and closed oscillation circuits of a trans-
mitter or receptor are adjusted so that both will permit the

GLOSSARY 279

electric oscillations to surge through them with the same fre-
quency, they are said to be tuned. Tuning refers only to the
adjustment of the sending circuits, or of the receiving circiits,
while syntonization refers to the adjustment of the sendin; to
the receiving circuits.

Unidirectional discharge. See Discharge.

Variable inductance coil. See Inductance Coil.

Vertical wire. See Aerial.

Value. The amount or quantity or magnitude or number.

Vibrations. The exceedingly rapid succession of to-and-fro move-
ments over the same path. Light-waves are vibrations of the
ether. Oscillations are much slower than vibrations, and
alternations are very slow compared to oscillations.

Voltage. The electromotive force expressed' in volts.

INDEX

PAGE

Abstract Sheets 238

Accumulator, Chloride 44

Acknowledgment of Receipt 232

Action of Apparatus 139

Action of a Coherer 153

Condenser 142

Conductive-coupled Receiving System 150

Sending System 146-148

Crystal Detector 155

Electrolytic Detector 154

Induction Coil 139

an Inductive-coupled Receiving System , 151

a Magnetic Detector 155

Morse Register 153

a Polarized Relay 153

Receiving System .* 150

Simple Sending System 144

Tapper 153

Transformer 142

Adjustable Condenser, for Sending 43

Leyden-jar Condenser 57

Spark-gap 56

Adjusting Aerial Wire to Emit a Given Wave-length 163

the Coherer 169

an Electroljrtic Interruptor 159

a Mercury Turbine Interruptor^ 158

the Morse Register ..,,.,., i 7q

2&2 INDEX

PAGE

Adjusting and Operating the Instruments i . . 157

the Relay 1C9

Spark-gap iCo

a Spring Interrupter 158

the Tapper 1 70

Adjustment of Crystal Detector Receptor 1 74

Electrolytic Detector Receptor 173

Instruments in the Primary Circuit 158

Magnetic Detector Receptor 1 74

Receiving Instriunents 169

Aerial, Electric Oscillations in an 30

Horizontal Flat-top, or T 82

Hot-wire Ammeter in i6r

Oblique 82

Portable 85

on S.S. Imperator 85-87

Straight Vertical 82

Switch 60

Suspension by Balloons loi

Umbrella 85-89

Wire 81

to Emit a Given Wave-length, Tuning the 162

System , 79

Capacity of 81

Coherer and Relay Circuits, Wiring Diagram

of 1 26

Changing the 38

Wires and Grounds for Field Work loi

Aerials, Aluminum Wire for Field loi

for Field Work loi

Types of 82

Airships, Wellman's Equipped with Marconi Apparatus 189

All Correct 226

Alphabetic Codes, Learning the 175

Alternating Current 22-45

Produced by Induction Coil 23

Aluminum for Detectors 75

Wire for Field Aerials loi

Ammeter • 47

Hot-wire 43, 61, 160

INDEX 283

PAGE

Analogue, Hydraulic, of Alternating Current 22

of Direct Current 20

of Tuned Oscillation Circuits 40

Anchor Gap 61

Apparatus in Action 139

of a Commercial Station 44

Arc Lamp, Oscillation 245-248

Army Enlistment Circular 220

Auto-detector Receptor, Commercial 71

Diagram of Simple 6-8

Experimental 14

Variable Condenser for 73

Balloons (or Aerial Suspension loi

Battery of Leyden-jars 43

Storage 44

Books on Wireless Telegraphy, List of 261

Box Kites loi

Braun-Siemens and Halske's system 193

Brush Discharge 27

Buzzer 70

Call Book, Wireless ... * 243

Calling of Stations 228

Capacity 30-38

of Aerial Wire System 81

Unit of 39

Carborundum for Auto-detector Receptor 16, 74

Care of a Morse Key 159

Spring Interruptor. . . . , 159

Cells, Dry 69

Edison 44

Polarized 68

284 INDEX

PAGE

Chalcopyritc 74, 75

Charges, Electric 36

Charging Aerial Wire System 39

and Counting, American and Canadian 237

Chart for Locating Ships in the Atlantic Ocean 215

Checking of Cipher Messages 233

Chloride Accimiulator 44

Choke Coils 68

Cipher Messages 235

Checking of 233

Circuit Connections for Receptors 121

Inductance of 39

Resistance of Oscillation 37

Circuits, Closed Oscillation 40

Conductively-coupled Oscillation 41

Constants of Oscillation 37

Diagram of Conductive-coupled Oscillation 114

Inductive-coupled Oscillation 115

Primary for Transmitters 114

Inductively-coupled Oscillation 42

Open Oscillation 40

Tuning Oscillation 43

Wiring Diagram of Internal 131

Clear Signal 225

Closed Core Transformer 54

Oscillation Circuits .40

Code Messages 235

Codes, Learning the Alphabetic 175

Wireless Telegraph , 176

Coherer, Action of a 153

Adjusting 169

Aerial Wire System and Relay Circuits, Wiring Diagram

of 1 26

How to Make a Simple lo

Marconi 63

Receptor, Commercial 63

Diagram of a Simple 4

Receptor, Experimental 10

Tuning a o 167

Coil, Induction 47

INDEX 285

PAGE

Coils, Choke 68

Collins Revolving Oscillation Arc. 250

Wireless Telephone Transmitter 254

Completion of Translation 225

Compound Words 236

Condenser 48

Action of 142

Adjustable Leyden-jar 57

for Sending 43

. Glass Plate 58

High Tension 58

for Induction Coil 52

Receiving 65-78

of Fixed Value 75-76

for Simple Auto-detector Receptor 15

Variable, for Receiving 76

Conduct! vely-coupled Oscillation Circuits 41

Receiving System, Action of 150

Resonator, Diagram of 1 24

Sending System, Action ot 146

Constants of Oscillation Circuits 37

Construction of Induction Coil 48

Masts 91

Continental Wireless Telegraph Code 181

Convective Discharge 27

Copies of Messages 232

Counting and Charging, American and Canadian 237

Coupled Oscillation Circuits 40, 11 2-1 15

Crystal Detectors 74

Detector, Action of a 155

Detector Receptors 74

Adjustment of 174

and Electrolytic Detectors, Wiring Diagrams for Receptors

with 135

Crystals 74

for Auto-detectors 16

Current, Alternating 22-45

Direct 20-45

High Potential 27

Hydraulic, Analogue of Direct 20

286 INDEX

PAGB

Current, Sources of 44

Unidirectional 37

Damped Electric Waves 245

Damping of Oscillations 37

De-coherers 67

Detector, Action of a Crystal ^ . . . 155

an Electrolytic 154

a Magnetic 155

Carborundum for Auto- 16

and Cell Circuit Diagram 122

Electrolytes for 76

Frame 75

Iron Pyrite for Auto- 16

Magnetic 71

Perikon 75

Receptor, Adjustment of Crystal 174

Electrolytic . . . •. 1 73

Magnetic 174

Receptors, with Crystal 74

Electrolytic 76

Magnetic 71

Silicon for Auto- 16

Simple, for Auto-receptor 15

Wiring Diagram for Receptor with Magnetic 132

Wollaston Wire for 77

Detectors, Metals for 74

Diagram of Action of a Conductive-coupled Receiving System 151

Sending System 147

an Inductive-coupled Receiving System 152

Sending System 149

a Simple Sending System 145

Concfuctive-coupled Resonator 1 24

Oscillation Circuits 114

Elementary of Detector and Cell Circuit 122

of Inductive-coupled Oscillation Circuits 115

Resonator 1 24

INDEX 287

PAGE

Diagram of Primary Circuits for Transmitters 1 14

a Simple Auto-detector Receptor 6-8

Coherer Receptor 4

Induction Coil Xransmitter 112

Opfen-circuit Resonator 122

Transformer Transmitter 112

Transmitter 2

Wiring of Aerial Wire System, Coherer and Relay Cir-
cuits 126

Complete Receptor 132

for Induction Coil with Electrolytic Interruptor, no

Independent Interruptor,

107, 108
Interruptor and Condenser. . .

106, 107
with Mercury-turbine Inter-
ruptor 109

of Internal Circuits 131

for Marconi Transmitter 118

Receptor 121

of. Relay Connections 126

for Receptor with Magnetic Detector 132

Receptors with Electrolytic and Crystal De-
tectors 135

Telefunken Transmitter 116

Transmitters 105

Direct Current 20-45

Produced by Primary Cell 21

Discharge, Brush 27

Convective 27

Disruptive 24-27

through Large Resistance 37

Small Resistance 38

Disruptive Discharge 24-37

Distance, Conditions Governing 80

Law of Signalling 80, 81

Distress Signals 224-242

Dry Cells 69

288 INDEX

PAGE

Eddy Kites loi

Edison Cells 44

Electric Charges 23, 36, 38

Discharge through Large Resistance 37

Small Resistance 38

Free Wave Theory 32

Oscillations 27

in an Aerial 30

Analogue of 27

Frequency of 30

How Produced 29

Sparks 24

Waves 24-30

Damped 245

Free 33

Law of 31

Length of 35

Means for Producing 244

Propagation of 31

Sliding 34

Sustained 245

Electrolyte 52

Electrolytes for Detector 76

Electrolytic and Crystal Detectors, Wiring Diagrams for Receptors

with 13s

Detector Receptor 76

Adjustment of 1 73

Interruptor 27, 48, 50

Adjusting an 159

Electrose Insulators 96

Elementary Diagram of Detector and Cell Circuit 122

Theory of Wireless 19

End of Work 224

Equipment, Makes of 177

Ether 24-35

Weight of 35

Experimental Auto-detector Receptor 14

Coherer Receptor. 10

INDEX 289

PAGE

Experimental Half-inch Induction Coil 8

Transmitter 8

I Farad, Unit of Capacity 39

I Field Aerials, Kites for loi

I Flat-top Aerial 82

Free Electric Waves .7 33

Frequency of Electric Oscillations 30

General Information for Operators 210

Generator for High Frequency Currents 245

Glass Plate Condenser 58

Glossary of Wireless Words, Terms and Phrases 271

Ground, How to Make a Gkxxi 96

Grounds 96

and Aerial Wires for Field Work loi

for Field Work 103

Henry, Unit of Inductance 39

High Frequency Generator 245

Grade Suspension 95

Potential Currents 27

Horizontal Aerial 82

Hot-wire Ammeter 43, 61, 160

in Aerial 161

How are Signals? 226

Hydraulic Analogue of Alternating Current r 22

of Direct Current 20

290 INDEX

PAGE

Impedance Coil 56

Inductance 30-39

of a Circuit 39

Coil for Conductive-coupled Circuits 58

Inductive-coupled Circuits 58

Variable 43 -58

Coils 58

Unit of 39

Induction Coil, Action of 139

Construction of 48

Condenser 52

with Electrolytic Interruptor, Wiring Diagram for . no

Half-inch, Experimental 8

with Mercury-turbine Interruptor, Wiring Diagram

for 109

Ten-inch 47

Transmitter, Diagram of. 112

Wiring Diagram for 106, 107

Independent Interruptor 107

Self- 39

Inductive-coupled Resonator, Diagram of 1 26

Receiving System, Action of 151

Sending System, Action of 148

Inductively-coupled Oscillation Circuits 42

Inductor 48

Infra-red Radiation 36

Instructions for Naval Operators 239

Instruments, Adjusting and Operating the 157

Adjustment of Receiving 169

Receiving Commercial 63

in the Primary Circuit, Adjustment of 158

Sending 44

Insulators, Electrose 96

Strain 93

International Signalling Code 224

Interruptor, Adjusting an Electrolytic 159

a Mercury-turbine 159

Spring : 158

INDEX 291

PAGE

Interruptor, Care of a Spring 159

Electrolytic 27, 48-50

Independent Spring 107

Mercury-turbine 48, 50, 109

Purpose of 142

Vibrating Spring 48

Interruptors 48

Iron for Detectors 75

Pyrites 74

for Auto-detector Receptor 16

Key for Auto-detector Receptors 46

Coherer Receptor 45

with Condenser 45

Magnetic Blowout 46, 116

Keys with Condensers no

Morse 45, no

with Oil Breaks , 112

Kites, Blue Hill Box loi

Eddy Malay loi

for Field Aerials loi

I-,aw of Electric Waves 31

Leading-in Insulator 95

Method 96

Learning the Alphabetic Codes 175

Length of Electric Waves 35

Leyden-jar Battery 43

Charge of a 23

Condenser, Adjustable 57

Light Waves 36

List of Books on Wireless Telegraphy . . ' 261

Type of Apparatus Used in U. S. Naw 216

U. S. Army Stations 217

Navy Ships and Shore Stations 217

392 INDEX

PAGE

Locating Ships in the Atlantic Ocean 215

Logs 238

Low-voltage Meters 47

Magnetic Detector 71

Action of 155

Receptor 71

Adjustment of 174

Tuning Coil 72

Makes of Equipment 177

Malay Kites loi

Marconi Company Offices 216

Magnetic Detector Receptor 187

Stations along the Atlantic Seaboard 214

Transmitter, Wiring Diagrams for 118

Wireless Telegraph System 179

Maritime Intelligence 232

Masts 86

Construction of 91

Portable 92

Rigging for 91

U. S. Navy 91

Mercury-turbine Interruptor 48, 50, 109

Adjusting a 158

Message, Order of a 226

Messages, Charging for 235

Checking of Cipher ^32

in Cipher 235

in Code 235

Not Accepted for Transmission 236

Numbering of 226

in Plain Language 235

Regulations for Public 234

Reply to a Service 225

Timing 227

Transmission of 228

Wording of 235

INDEX 293

PAGE

Metals for Detectors 75

Meters, Low Voltage 47

Microfarad 39

Millihenr>' 39

Molybdenum for Detectors 75

Morse Alphabetic Code 1 78

Keys 45

Care of 1 59

Registers 45, 67

Naval Operators, Instructions for 239

Navy Wireless Telegraph Code 1 79

Non-inductive Resistance 64

Numbering of Messages , 226

Oblique, Aerial 82

Ohm, Unit of Resistance 38

Oil-cooled Transformer 56

Open-core Transformer 54

Open-oscillation Circuits 40

Operating and Adjusting the Instruments 157

Room, Size of 98

Operators, Instructions for Naval 239

Service Regulations for 223

Suggestions to 210

Order of a Message 226

Oscillation Arc Lamp 245-248

Circuits 40

Analogue of Tuned 40

Closed 40

Conductively-coupled 41

Constants of 37

Diagram of Conductive-coupled 114

294 INDEX

PAGE

Oscillation Circuits, Diagram of Inductive-coupled. . , , * ^ 115!

Inductively-coupled >. 42

Open 40

Resistance of 37

Tuning 43

Transformer 42-58

for Receiving 78

Oscillations^ Analogue of 27

Damping of 37

Electric 27

in an Aerial 30

Frequency of 30

How Produced 29

Oscillator System 31

Perikon Detector 75

Phosphor-Bronze for Detectors 75

Platinum Wire for Detector 77

Polarized Cells 68

Relay 65

Action of 153

Portable Aerial 85

Mast 92

System, Signal Corps, U. S. A 194

Positions, Where to Apply for 218

Practical Application of the Arc to Wireless Telephony 249

Primary Coil 48

Priority 226

Propagation of Electric Waves 31

Radiations, Infra-red 36

Ultra-violet » 36

Rates for Wireless Messages 212

Ratio of Transformation 142

Reactance Coil 56

INDEX 2?S

. .. .. PAGE

Receivers, Telephone - 7^

Receiving Instruments 63

Adjustment of 169

Condenser 78

Fixed Value 75*76

Variable 73

System, Action of 150

an Inductive-coupled 151

Conductive-coupled 150

Tuning Oscillation Transformer 78

Coil 76

Three Slide 64

Receptor, Adjustment of Crystal detector 174

Electrolytic Detector 173

Magnetic Detector 174

Carborundum for Auto-detector 16

Circuit Connections for 121

Commercial Auto-detector . . . ; 71

Coherer 63

Condenser for Simple Auto-detector 15

Detector for Simple Auto 15

Diagram of a Simple Coherer 4

Auto-detector 6-8

Electrolytic Detectors 76

Experimental Coherer. 10

Auto-detector 14

Iron Pyrites for Auto-detector 16

Magnetic Detector 71

Pony Relay for Experimental Coherer 12

Silicon for Auto-detector 16

Testing the 173

Tuning a Coherer 167

for Wireless Telephony 256

Wiring, Diagram for Magnetic Detector 132

Complete 132

Receptors with Crystal Detectors 74

with Electrolytic and Crystal Detectors, Wiring Dia-
grams for 135

Wiring, Diagram for 121

a$6 mOBX

PAGE

Regulations for Commercial Operators 223

in Public Messages 234

Relay, Adjusting the 169

Coherer and Aerial Wire System Circuits, Wiring, Diagram

of 126

Connections, Wiring Diagram of 126

Polarized 65

Pony for Experimental Coherer Receptor 12

Testing Coil 69

Relays 65

Reply to a Service Message 225

Report, General 238

Technical 238

Reports 238

Request for Repetition 225

Resistance o 30-37

Coil 56

Discharge through Large 37

Small 38

Non-inductive 64

of Spark-gap 37

Resonator, Diagram of Conductive-coupled 1 24

Inductive-coupled 1 24

Simple Open-circuit 122

Retransmission 224

Rheostat 56

Ruhmkorff Coil (see Induction Coil).

Secondary Coil 48

Self-induction 39

Sending Instruments 44

System, Action of a Conductive-coupled 146

Inductive-coupled 148

Simple 144

Signal Corps, U. S. A., Portable System 194

Signalling Distance 79» 224

Signals, Distress 242

INDEX 297

PAGE

Signs and Prefixes 224

Silicon 74

for Auto-detector Receptor 16

Simple Coherer 10

Slide Tuning Coil 15

Wireless Telegraph System i

Slaby-Arco System 193

Sliding Electric Waves 34

Half-wave Theory 32

Sources of Current 44

Spark-gap, Adjustable 56

Adjusting the 160

Resistance of 37

Spark-gaps 56

Sparks, Electric , 24

Spring Interruptor 48

Station, Apparatus of a Commercial 44

Storage Battery 44

Strain Insulators 93

Suggestions to Operators 210

Suspension of Aerials 93

Balloons for Aerials loi

High Grade 93, 95

Simple Method of 93-94

Switch, Aerial 60

Systems of Wireless Telegraph 177

T Aerial 82-85-

Tapper, Adjusting the 1 70

Action of 153

Tappers 67

Telefunken Svstem 191

Transmitter, Wiring Diagram for 116

Telegraph Codes, Wireless 176

Telephone Receiver, Adjustable Head 74

Receivers 76

Tellurium for Detectors 75

298 INDEX

PAGE

Testing the Receptor 1 73

Box 70

Coil for Relay 69

Theory of Electric Oscillations 27

Free Electric Waves 31

Oscillation Arc 251

Sliding Half Waves 32

Wireless, Elementary 19

Timing Messages 227

Trans-atlantic Cableless Station at Glac6 Bay 207

Transformation, Ratio of 142

Transformer 54

Action of 142

Closed-core 54

Oil-cooled 56

Open-core . . 54

Oscillation 42

for Receiving, Oscillation 78

Transmitter, Diagram of Simple 112

Transmission of Messages * . 228

Transmitter, Diagram of a Simple 2

Diagram of Simple Transformer 112

Induction Coil 112

Experimental 8

Timing a Coupled 160

Wireless Telephone 246

Wiring Diagram for Marconi 118

Wiring Diagram for Telefunken 116

Transmitters, Diagram of Primary Circuits for 114

Tuning Device for 164

Wiring Diagrams for 105

Tuned Oscillation Circuits, Analogue of 40

Tuner 69

Tuning the Aerial Wire to Emit a Given Wave Length 162

a Coherer Receptor « 167

Coil for Conductive-coupled Circuits 58

Inductive-coupled Circuits 58

Magnetic Detector Receptor 72

Receiving 76

Simple Auto-detector Receptor 15

INDEX 299

PAGE

Tuning Coil, Three-slide Receiving 64*

Two-slide ^ 73

Variable 59

Coils 58

a Coupled Transmitter 160

Device for Transmitters 164

Oscillation Circuits 43

Transformer for Receiving 78

Types of Aerials 82

Ultra-violet Radiations > 36

Umbrella Aerial 85-89

Unidirectional Current 37

Unit of Capacity 39

Inductance 39

United System 206

Variable Condenser, for Auto-Detector Receptor 73

Receiving 76

Inductance Coil 43

Tuning Coil 59

Vertical Straight Aerial 82

Vibrators (see Interruptors) 48

Voltmeter 47

Wave-length, Tuning the Aerial Wire S.vstem to Emit a Given 162

Used by U. S. Navy 164

Waves, Damped Electric 245

Electric 24-30

Free Electric ^z

Law of Electric 31

Length of Electric 35

Light 36

300 . INDEX

PAGE

Waves, Propagation of Electric 31

Sliding Electric 34

Sustained Electric 245

Theory of Sliding Half- Waves 32

Tree Electric 31

Weight of Ether 35

Wellman's Airship Equipped with Marconi Apparatus 189

Wire, Aerial 81

for Detector 77

Wiring Diagram of Aerial Wire System, Coherer and Relay Circuits 126

Complete Receptor 132

for Induction Coil with Electrolytic Interruptor .. no

Interruptor and Condenser. . 106-107
with Independent Interruptor.

107-108
Mercury-turbine Interrup-
tor 109

<rf Internal Circuits 131

for Marconi Transmitter 118

Receptors 121

Electrolytic and Crystal Detectors. . 135

Magnetic Detector 132

of Relay Connections 1 26

for Telefunken Transmitter 116

Transmitters 105

Wireless Call Book 243

Class in Navy Yard School 201

Messages, Rates for 212

Telegraph Codes 176

Systems 177

System, Simple i

Telephony 244

Words, Terms, and Phrases, Glossary of 271

WoUaston Wire for Detector 77

Wording of Messages 23S

^incite 74

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